DFSDCxxx member of the IMS PROCLIB data set

You can find an example of the DFSDCxxx member of the IMS PROCLIB data set, DFSDC000, in library SDFSSLIB.

The DC= parameter in the IMS or DCC startup procedure defines the DFSDCxxx PROCLIB member that is used. The default suffix is 000.

Environments

The DFSDCxxx member of the IMS PROCLIB data set applies to the DB/DC and DCCTL environments.

Restrictions

If you use the DFSDCxxx member to override a default name (from system definition), do not specify a statically defined lterm or node name.

If you use the DFSDCxxx member to override the master or secondary master node names, do not specify a statically defined node name.

If you use the DFSDCxxx member to override the master or secondary master LTERM names, do not specify a statically defined LTERM name.

If you use the DFSDCxxx member to override the generic LTERM name of the master LTERM or secondary master LTERM, do not specify a statically defined LTERM name.

The node that you specify using the PMTO or SMTO parameters must have the same physical characteristics as the default node that you are overriding. For example, you cannot override a SLU2 device with a non-SNA device.

If you change the PMTO=, SMTO=, PMOTn=, or SMTOn= control statements in the DFSDCxxx member, you must perform a cold start of IMS. You can perform a warm start for changes to any other control statements in the DFSDCxxx member.

Usage

A DFSDCxxx member consists of one or more 80-character records. You code keyword parameters in positions 1-71. Positions 72-80 are ignored. Keywords can contain leading and trailing blanks. If you specify multiple keywords in a record, use commas as delimiters.

Parameters

AOS=

AOS=N

Specifies that shared message queue support for synchronous APPC/OTMA is not active. The default is inactive (N).

AOS=Y

Specifies that shared message queue support for synchronous APPC/OTMA is active (Y). Shared message queue (SMQ) support for APPC/OTMA enables IMSplex users to execute transactions that are originated by APPC or OTMA on a back-end system.

If AOS=Y, transactions with SYNCLVL=SYNCPT are processed with RRS as the synchronization point manager.

AOS=F

Activates the function by force (F) even if another member in the IMSplex cannot activate the function.

APPC/OTMA SMQ enablement uses z/OS® Resource Recovery Services (RRS) multiSystem cascaded transactions to synchronize IMS systems. If RRS is not active on one system, the systems that have specified F (force) still queue incoming transactions without any affinity. Therefore, if a system without RRS tries to process one of these transactions, IMS abends the application with a U711 code.

AOS=B

Specifies that APPC and OTMA use z/OS cross-system coupling facility (XCF) to communicate between the front-end and the back-end systems for synchronous transactions with sync level of NONE and CONFIRM.

If RRS=Y, transactions with synchronization level of NONE or CONFIRM are processed at the back end using XCF communication. Transactions with sync level of SYNCPT are processed at either the front-end or back-end systems, using RRS.

If the back-end system has RRS=N, transactions with synchronization level of NONE or CONFIRM are processed at the back end using XCF communication. Transactions with sync level of SYNCPT are processed only at the front-end system. However, if the front-end system also has RRS=N, transactions with sync level of SYNCPT are not processed at all.

AOS=B requires a MINVERS value that is set to 12.1 or later.

AOS=S

Specifies that APPC and OTMA use XCF to communicate between the front-end and the back-end systems for synchronous transactions with sync level of NONE and CONFIRM and RRS multiSystem cascaded transactions for synchronous transaction with sync level of SYNCPT.

For synchronous transaction with sync level of SYNCPT, the functionality of AOS=S is equivalent to the AOS=F specification, meaning that if RRS is not active on one system, the systems that have specified S (force) still queue incoming transactions globally without any affinity. If a system without RRS tries to process one of these transactions, IMS abends the application with a U711 code.

The back end starts either the new XCF message processing or the existing RRS message processing depending on whether the message has the XCF indicator or the RRS indicator.

AOS=S requires a MINVERS value that is set to 12.1 or later.

AOS=X

Specifies that APPC and OTMA use XCF to communicate between the front-end and the back-end systems for synchronous transactions with sync level of NONE and CONFIRM.

RRS is not used for synchronous transactions with sync level of SYNCPT. In this case, specifying AOS=X is equivalent to specifying AOS=N.

The X parameter is applicable only to the front-end system. The back-end system is not required to specify this parameter.

The back end starts either the new XCF message processing or the existing RRS message processing depending on whether the message has the XCF indicator or the RRS indicator.

AOS=X requires a MINVERS value that is set to 12.1 or later.

Important: By default, APPC/OTMA shared message queue support is deactivated for all the members within the IMSplex, except for members where the F (force) option is specified.

AOSLOG=

Specifies for APPC and OTMA whether (Y) or not (N) the front-end system writes an X'6701' log record for the following cases:

• Response message returned from the back-end system by XCF for transactions with synchronization levels of NONE, CONFIRM, and SYNCPT.
• Error message returned from the back-end system by XCF for transactions with all synchronization levels of NONE, CONFIRM, and SYNCPT.

AOSLOG=Y

Indicates that the front-end system logs the X'6701' record.

AOSLOG=N

Indicates that the front-end system does not log any X'6701' record. AOSLOG=N is the default value.

The AOSLOG parameter is applicable only to the front-end system. The back-end system is not required to specify this parameter.

APPCASY=

Specifies whether (Y) or not (N) a non-response transaction originating from a program-to-program switch should be scheduled asynchronously or synchronously (S). In a shared-queues environment, the originated transactions usually maintain affinity with the system in which the originating transaction was processed, unless APPCASY is set to S (and AOS=Y).

If you specify APPCASY=S, the first program-to-program switch that can continue the synchronous conversation is synchronous. Every further program switch is asynchronous.

If you specify APPCASY=S, the OTMAASY value is S. If you specify OTMAASY=S, the APPCASY value is S.

In a shared-queues environment where the support for synchronous APPC/OTMA is active (AOS=Y), if you specify APPCASY=S, the program-to-program switch transactions do not have any affinity.

The default is APPCASY=Y.

Asynchronous transactions have no affinity.

Recommendation: Use the default specification of APPCASY=Y.

Restriction: This parameter applies to synchronous transactions only.

APPCIOT=(mmmm:ss,mmmm)

Specifies the APPC timeout values in minutes and seconds. Valid values for mmmm are 00 to 1440. Valid values for ss are 00 to 59. If APPCIOT=00, there is no timeout detection.

The first parameter specifies the APPC/MVS™ timeout value. This is the number of minutes or seconds an APPC/MVS service is allowed to wait for completion.

The second parameter specifies the APPC/IMS timeout expression. This is the number of minutes an application is allowed to be inactive and is for synchronous conversations only. Inactive means that the application was not able to respond within the timeout limit.

Note: In some cases, IMS cannot determine if an APPC conversation is synchronous or asynchronous. This situation occurs in program-to-program switches, where IMS cannot predict which program continues the synchronous APPC conversation.

Requirement: Changing this parameter after a previous IMS start does not require a cold start. You must restart IMS, however, to allow the new specification to take effect.

APPCLLU=

Identifies a local LU to be used for outbound message processing.

N

The base LU is used for asynchronous message responses to the IOPCB. This is the default.

Y

The incoming local LU is used as the local LU for asynchronous message responses to the IOPCB.

APPCRCV=

Specifies whether IMS should pass the first segment to the DFSNPTR0 or DFSMSCE0 exit. The default is Y. If N is specified, IMS calls the exits before receiving the first segment.

ASSNCHANGE=NOSAVE  | SAVE

Sets the default value for the /ASSIGN LTERM|USER TO USER command. SAVE specifies that LTERM assignments (made in ETO) are retained across session and IMS restarts (the user and LTERM control blocks are not deleted). The default is NOSAVE, which indicates that the assignment is not retained and the user and LTERM control blocks are deleted.

You can override the ASSNCHANGE control statement by specifying SAVE or NOSAVE on the /ASSIGN command. If you issue the /ASSIGN command without specifying SAVE or NOSAVE, IMS uses the default value that is specified on the ASSNCHANGE control statement.

Requirement: Changing this parameter after a previous IMS start does not require a cold start. You must perform a warm start, however, to allow the new specification to take effect.

AUTHLOG=ALL  | NOMSG | NONE

Determines whether to suppress a RACF® ICH408I message to the system console, and whether to turn on SMF logging. This determination takes place after an AUTH call issued by an IMS application program fails authorization.

ALL

IMS turns on SMF logging, and the RACF ICH408I message is issued. ALL is the default.

NOMSG

IMS turns on SMF logging when appropriate, and the RACF ICH408I message is suppressed.

NONE

SMF logging is not turned on, and the RACF ICH408I message is suppressed.

AUTLCHANGE= NOSAVE  | SAVE

Sets the default value for the /CHANGE USER AUTOLOGON command. SAVE specifies that autologon changes made in ETO are retained across session and IMS restarts (the user control block are not deleted and remain in effect across a restart or XRF takeover until another /CHANGE command with the NOSAVE parameter is issued). The default is NOSAVE, which indicates that the autologon changes are not retained across session and IMS restarts (the user control block is deleted).

You can override the AUTLCHANGE control statement by specifying SAVE or NOSAVE on the /CHANGE command. If you issue the /CHANGE command without specifying SAVE or NOSAVE, IMS uses the default value that is specified on the ASSNCHANGE control statement.

Requirement: Changing this parameter after a previous IMS start does not require a cold start. You must perform a warm start, however, to allow the new specification to take effect.

BMPUSID=PSBNAME | USERID

Specifies the system option for the value to be placed in the user ID field of the message prefix for a message generated by a non-message driven BMP and the value to be used for the userid for CHNG and AUTH calls made by a non-message-driven BMP.

• If BMPUSID=USERID is specified, the value from the USER= keyword on the JOB statement is used.
• If USER= is not specified on the JOB statement, the program's PSB name is used.
• If BMPUSID=PSBNAME is specified, or if BMPUSID= is not specified at all, the program's PSB name is used. If PSBNAME is not defined to RACF, the Userid of the current Address Space will be used; this will be the Home Dependent Region one, or the Control Region one if LSO=Y or if PARDLI=1 has been specified for the BMP. Userid of the current Address Space will be used also if DFSBSEX0 has returned RC08.

Note: This parameter is not valid for DBCTL. The value from the USER= keyword on the JOB statement is used for a JBP.

Requirement: Changing this parameter after a previous IMS start does not require a cold start. You must perform a warm start, however, to enable the new specification to take effect.

GENIMSID=

A 1- to 8-character alphanumeric shared IMS ID that identifies a TCP/IP generic resources group in an IMSplex.

Each MSC-enabled IMS system in the IMSplex that participates in the TCP/IP generic resources group must specify the same shared IMS ID on the GENIMSID parameter.

The IMS Connect instance that supports TCP/IP generic resources group in the IMSplex must also specify the shared IMS ID on the GENIMSID parameter of the IMS Connect MSC configuration statement for each participating IMS system.

MSC-enabled IMS systems outside of the IMSplex connect to the IMSplex by specifying the shared IMS ID on the NAME parameter of the MSPLINK macro statement that defines a TCP/IP-type MSC physical link to the IMSplex. The IMS systems outside of the IMSplex do not need to define a MSC links to specific IMS systems in the IMSplex.

New connections to the TCP/IP generic resources group are accepted by the first IMS system to respond to the connection request when it is passed to the IMSplex by IMS Connect. After the connection has been accepted by a participating IMS system, the MSC physical link and all logical links assigned to it have affinity with that IMS system until the link is terminated.

The IMS ID must begin with an alphabetic character.

The value of GENIMSID cannot be the same as the IMS ID of any IMS system in the IMSplex or of any remote IMS system that connects to the IMSplex by using an MSC TCP/IP link.

GRAFFIN=IMS | VTAM®

This keyword is obsolete and is ignored.

GRESTAE=Y | N

Specifies whether IMS should bypass the VTAM generic resource logic in the IMS ESTAE exit.

Y indicates that IMS should continue the existing ESTAE logic to delete affinity for all nodes where no status remains before closing the ACF/VTAM ACB.

N indicates that IMS should close the ACF/VTAM ACB immediately to expedite IMS termination, and leave affinity for all nodes set.

Requirement: Changing this parameter after a previous IMS start does not require a cold start. You must perform a warm start, however, to allow the new specification to take effect.

GRMESTAE=Y | N

Indicates whether MSC link affinity should be deleted.

Y

During an IMS abend, IMS calls the ESTAE routine in the control region and deletes the affinity setting of any MSC link that does not have a significant status requiring the link session to connect to the same IMS in the IMSplex. This is the default.

N

IMS does not delete MSC link affinity in the ESTAE routine.

Significant status for MSC means that the link is in ERE mode. Use the /DIS LINK command to display status.

IMSWT=IMSWT | nnnnn

Specifies up to 5 characters that are appended with a 3-character line number yyy to make up the full JOBNAME (nnnnnyyy) in the /STA REGION jobname for the auto-scheduled spool print utility. If IMSWT= is not specified or if nnnnn is blank, IMS uses the default value of IMSWT (IMSWTyyy).

Requirement: Changing this parameter after a previous IMS start requires a cold start to take effect.

ISCTCPIP=(nodename,iconname)

Sets a static LU 6.1 ISC terminal to use TCP/IP communication protocols.

The nodename value is the name of an LU 6.1 ISC terminal, as specified on the NAME parameter of the TERMINAL macro that is part of the terminal system definition.

The iconname value is the IMSplex name of a local IMS Connect instance that manages TCP/IP communications for this IMS. The iconname value must match the name specified on the MEMBER parameter of either the ISC statement or the IMSplex statement in the IMS Connect configuration PROCLIB member (HWSCFGxx). The name specified in the iconname position must start with an alphabetic character and can be 1- to 8-alphanumeric characters long.

LU 6.1 terminals are the only static ISC terminals that support TCP/IP. Terminals are defined as LU 6.1 during stage 1 system definition by UNITYPE=LUTYPE6 on the TYPE macro. If the terminal referenced by the nodename value is not LU 6.1, an error message is issued and the non-LU 6.1 terminal is unchanged.

The nodename value must be unique among all node names specified on ISCTCPIP keywords in the DFSDCxxx member. If the node name is not unique, each subsequent specification of the node name is rejected and an error message is issued.

Requirement: After IMS is started, any changes to this parameter require a cold start before they can take effect.

TCP/IP support for ISC is provided by IMS Connect. If you are setting up ISC TCP/IP support for the first time, you must also code the appropriate configuration statements in the IMS Connect PROCLIB member, including the ISC and RMTCICS statements.

LOCKSEC=Y | N

When password protection is used for the /LOCK and /UNLOCK commands, specifies whether (Y) or not (N) calls to RACF security and the Transaction Authorization exit routine (DFSCTRN0) are made. When LOCKSEC=Y is specified, the command is processed if either of the following is true:

• The resource specified by the command is defined to RACF and the user is authorized to use the resource.
• The resource is not defined to RACF.

If the resource is defined to RACF, but the user is not authorized to use the resource, the command is rejected with the message DFS3689W.

MFSPFV=N | Y

N

The Message Format Service (MFS) function does not check the content of a protected field that is returned from a 3270 or SLU2 device.

Y

The MFS function checks the content of a protected field that is returned from a 3270 or SLU2 device. If the MFS detects that protected data in the input is altered from the content that was transmitted to the device, it ignores the input with message DFS573.

MSCSEC=

Specifies the security options for direct and non-direct routed transactions received from an MSC link.

LRDIRECT

Specifies that Link Receive routing use RACF, the Transaction Authorization exit routine (DFSCTRN0), or both to check security for direct routed transactions. This is the default.

LRNONDR

Specifies that Link Receive routing use RACF, the Transaction Authorization exit routine (DFSCTRN0), or both to check security for non-direct routed transactions. No security checking is performed for direct routed transactions.

LRALL

Specifies that Link Receive routing use RACF, the Transaction Authorization exit routine (DFSCTRN0), or both to check security for direct and non-direct routed transactions.

LRNONE

Specifies that the IMS subsystem does not request any security checking for either type of transaction.

CTL

Specifies that RACF security is to authorize the use of the transaction based upon the user ID of the IMS control region.

MSN

Specifies that RACF security is to authorize the use of the transaction based upon the user ID of the MSNAME.

USR

Specifies that RACF security is to authorize the use of the transaction based upon the user ID of the inputting terminal.

EXIT

Specifies that authorization is performed by the Transaction Authorization exit routine (DFSCTRN0).

CTLEXIT

Specifies that both RACF security and the Transaction Authorization exit routine (DFSCTRN0) are used to authorize the IMS control region user ID to use the transaction.

MSNEXIT

Specifies that both RACF security and the Transaction Authorization exit routine (DFSCTRN0) are used to authorize the MSNAME to use the transaction.

USREXIT

Specifies that both RACF security and the Transaction Authorization exit routine (DFSCTRN0) are used to authorize the user ID of the inputting terminal to use the transaction.

NONE

Specifies that no security authorization checking is performed.

MSCVGR=N | Y

Specifies whether MSC links use the GRSNAME or the APPLID name in an IMS VGR environment.

Y

IMS attempts to use the GRSNAME first to establish the session with the remote IMS. The remote IMS must use the value of the MSPLINK NAME=nodename for the IMSplex GRSNAME.

N

The APPLID name, not the GRSNAME, is used in an IMS VGR environment. This is true also if the remote IMS uses the IMSplex nodename. This is the default.

MTOUSID=

Specifies a user ID that IMS uses if the primary MTO does not sign on for transaction authorization checking.

If you do not specify MTOUSID, the control region's user ID is used for any other terminal that does not sign on.

OUTBND=

Specifies a different outbound LU. The specified LU must be one of the APPC LUs defined in the APPCPMxx member of the SYS1.PARMLIB library. The default outbound LU is BASE LU.

PMTO=name1 | (name1) | (name1,name2)

name1 specifies the node name of the primary master terminal (PMTO). This name overrides the PMTO node name that is specified during IMS system definition.

name2 specifies the name of the additional PMTO resource that exists in an XRF environment. If name2 is specified in a non-XRF environment, it is ignored.

If the PMTO parameter is not specified, the default PMTO name (either one or both) that was specified during IMS system definition is used.

Requirement: Changing this parameter after a previous IMS start requires a cold start to take effect.

PMTO1-8=name | (name) | (name,MASTER)

Specifies the first through the eighth LTERM names of the PMTO. The names you specify here override the first through the eighth LTERM names specified during IMS system definition. The LTERM name specified with the MASTER designation becomes the PMTO LTERM. These LTERM names must be unique for each IMS system within a shared IMS environment.

Requirement: Changing this parameter after a previous IMS start requires a cold start to take effect.

PMTOG=DFSPMTO | name

Specifies the generic LTERM name of the PMTO. The default is DFSPMTO. Use the same generic LTERM name for each IMS system within a shared IMS environment.

Requirement: Changing this parameter after a previous IMS start requires a cold start to take effect.

PSTIMER=3600 | xxxxx

When Rapid Network Reconnect (RNR) is used, the PSTIMER= parameter specifies a one- to five-digit number indicating the number of seconds IMS can wait pending recovery for persistent sessions following an IMS or ACF/VTAM failure. The restarted IMS must successfully issue an OPEN ACB before the timer expires or the sessions are terminated. Valid values are from zero (no timer) to 86,400® seconds (24 hours). The IMS default is 3600 seconds (1 hour). If a null or invalid value is specified, IMS uses 3600.

When an ACB name is specified on the MNPS= keyword (in the PROCLIB member DFSHSBxx or DFSPBxxx, or in the IMS procedure), specifies the amount of time before the XRF alternate must successfully open the MNPS ACB. This applies to an XRF takeover only. It does not apply to an emergency restart because persistent sessions are not restored following a restart in an XRF system using MNPS.

Requirement: Changing this parameter after a previous IMS start does not require a cold start. You must perform a warm start, however, to allow the new specification to take effect.

RACFMSG= N | Y

Determines whether IMS passes RACF sign-on messages to the Greeting Message exit routine (DFSGMSG0) when a user successfully signs on to IMS.

N

IMS does not pass RACF sign-on messages to the DFSGMSG0 user exit routine. This is the default value.

Y

When a user successfully signs on to IMS, IMS passes RACF sign-on messages, such as ICH70001 and ICH70002, to the DFSGMSG0 user exit routine.

RCLASS=

Specifies a 1- to 7-character alphanumeric subsystem identifier for the RACF resource classes for this IMS subsystem. Use the RCLASS= parameter to uniquely identify the resource classes for this IMS subsystem in RACF.

RACF appends the subsystem identifier to a resource class identifier to create the full name of each IMS resource class in RACF. For example, if you specify RCLASS=IMS123, the name in RACF of the IMS transaction authorization resource class for this subsystem would be "TIMS123", because the resource class identifier for IMS transaction authorization is "T". And the name of the IMS command authorization resource class for this IMS subsystem would be "CIMS123".

Defining different subsystem identifiers can be useful for restricting access to resources in one subsystem, while allowing access to those same resources in another. For example, if a production subsystem has a subsystem identifier of IMSPROD and a test subsystem has a subsystem identifier of IMSTEST, an application programmer could then be authorized to TRAN01 in the TIMSTEST transaction authorization resource class, but not to TRAN01 in the TIMSPROD transaction authorization resource class.

The RCLASS= specification in the DFSPBxxx PROCLIB member overrides the RCLASS= specification in the DFSDCxxx PROCLIB member.

RACF uses "IMS" as the default subsystem identifier for IMS subsystems.

RCVYCONV=

Specifies whether the status of a conversation can be recovered (YES) or not (NO). RCVYCONV applies to conversation status, not to output messages. Even if the conversation status is not recovered, conversation output continues to be recoverable and is delivered asynchronously.

The following table describes the default values for RCVYCONV as they relate to the values specified on the SRMDEF keyword.

Table 1. RCVYCONV values related to SRMDEF values

SRMDEF value	RCVYCONV=YES	RCVYCONV=NO
SRMDEF=GLOBAL	Valid (default)	Valid
SMRDEF=LOCAL	Valid (default)	Valid
SRMDEF=NONE	Invalid	Valid (default)

If RCVYCONV is specified incorrectly, message DFS1920I is issued and IMS uses the appropriate default from Table 1.

RCVYFP=

Specifies whether the status of Fast Path can be recovered (YES) or not (NO). RCVYFP applies to Fast Path status and output.

The following table describes the default values for RCVYFP as they relate to the values specified on the SRMDEF keyword.

Table 2. RCVYFP values related to SRMDEF values

SRMDEF value	RCVYFP=YES	RCVYFP=NO
SRMDEF=GLOBAL	Valid (default)	Valid
SRMDEF=LOCAL	Valid (default)	Valid
SRMDEF=NONE	Invalid	Valid (default)

Restrictions: If SRMDEF=LOCAL, STSN recoverability (RCVYSTSN) and fast path recoverability (RCVYFP) must be the same. They must both specify YES or both specify NO.

If RCVYFP is specified incorrectly, message DFS1920I is issued and IMS uses the appropriate default from Table 2.

Related reading: For a discussion on the recoverability of Fast Path status, see Fast Path recovery.

RCVYRESP=

Specifies whether the status of full-function response mode can be recovered (YES) or not (NO). RCVYRESP applies to full-function response mode status, not to output messages. Even if full-function response mode status is not recovered, response mode output continues to be recoverable and is delivered asynchronously.

The following table describes the default values for RCVYRESP as they relate to the values specified on the SRMDEF keyword.

Table 3. RCVYRESP values related to SRMDEF values

SRMDEF value	RCVYRESP=YES	RCVYRESP=NO
SRMDEF=GLOBAL	Invalid	Valid (default)
SRMDEF=LOCAL	Valid	Valid (default)
SRMDEF=NONE	Valid. However, only those terminals or users that are assigned SRM=LOCAL as an override to SRMDEF=NONE (through user descriptor or user exit) are eligible to recover full-function response mode. All other terminals and users use RCVYRESP=NO.	Valid (default)

If RCVYRESP is specified incorrectly, message DFS1920I is issued, and IMS uses the appropriate default from Table 3.

Restrictions:

• RCVYRESP=YES is invalid when IMS is using an RM resource structure to maintain TM resources (that is, when STM=YES in the DFSDCxxx member of the IMS PROCLIB data set).
• RCVYRESP=YES applies only to terminals or users that have a status recovery mode of LOCAL. If a terminal or user has a status recovery mode of GLOBAL or NONE, the terminal or user is automatically assigned RCVYRESP=NO.
• Full-function response mode is not recovered following an IMS shut down or failure. After an IMS cold start, warm start, or emergency restart, the node or user is no longer in full-function response mode. Full-function response mode is recovered following an XRF takeover for class-1 terminals only.
• The RCVYRESP value specified cannot be overridden for individual users or nodes using either ETO user descriptors, the user logon exit (DFSLGNX0), or the user signon exit (DFSSGNX0). Therefore, RCVYRESP=YES automatically applies to all terminals and users with a LOCAL status recovery mode.

RCVYSTSN=

Specifies whether the status of STSN terminals (SLUP, FINANCE, and ISC) can be recovered (YES) or not (NO).

The following table describes the default values for RCVYSTSN as they relate to the values specified on the SRMDEF keyword.

Table 4. RCVYSTSN values related to SRMDEF values

SRMDEF value	RCVYSTSN=YES	RCVYSTSN=NO
SRMDEF=GLOBAL	Valid (default)	Valid
SRMDEF=LOCAL	Valid (default)	Valid
SRMDEF=NONE	Invalid	Valid (default)

Restrictions: If SRMDEF=LOCAL, STSN recoverability (RCVYSTSN) and fast path recoverability (RCVYFP) must be the same. They must both specify YES or both specify NO. If SRMDEF=GLOBAL, Fast Path is always nonrecoverable, so if there is a failure during the execution of a fast path transaction, the STSN session must be restarted cold.

If RCVYSTSN is specified incorrectly, message DFS1920I is issued and IMS uses the appropriate default from Table 4.

RNR=NRNR | ARNR | NONE

Specifies that IMS should enable Rapid Network Reconnect (RNR) support for ACF/VTAM persistent sessions as defined on the ACF/VTAM APPL statement for IMS. This parameter is used as a system default for an unspecified RNR value for the OPTIONS= keyword at the terminal level.

ARNR

Specifies that a basic session reconnect should be done automatically by IMS following an IMS or ACF/VTAM restart. This level of session reconnect is to a data traffic reset point equivalent to logon without available signon data. A DFS3649 signon required message can be sent as appropriate for the terminal type and definition.

NRNR

Specifies that automatic session reconnect should not be done. The session is terminated following restart of IMS or ACF/VTAM.

NONE

Specifies that the RNR function should not be activated. This option can also be used to deactivate the RNR function if it was activated before the IMS restart.

Requirement: Changing this parameter after a previous IMS start does not require a cold start, although a cold start is recommended in order to clear persistent session data in VTAM and terminate IMS sessions that are waiting for an RNR reconnection. You must perform at least a warm start to allow the new specification to take effect.

SAPPLID=appl_ID

Specifies the application ID to be used when calling RACF, or equivalent product, during sign on. If SAPPLID= is not specified, the IMSID of that IMS is the default application ID. The application ID becomes important when Passtickets are used instead of passwords because the application ID is used in the RACF creation and verification of the Passticket.

Requirement: Changing this parameter after a previous IMS start does not require a cold start. You must perform a warm start, however, to allow the new specification to take effect.

SECCNT=0 | 1 | 2 | 3

Specifies the maximum number of terminal and password security violations to be accepted per physical terminal and the number of transaction command violations per transaction prior to master terminal notification of such violations. The default is 0, which nullifies notification to the master terminal. The number specified must be 0, 1, 2, or 3.

SIGNON=SPECIFIC | ALL

Specifies that either all (ALL) or specific (SPECIFIC) static terminals are required to sign on.

ALL

Specifies that all static terminals (except the master terminal) are required to sign on. The following devices are not required to sign on when SIGNON=ALL is specified:

• LU6.1 devices
• 3284/3286 devices
• SLU1 printer-only devices
• Master terminals

  To require master terminals to sign on, specify the OPTIONS=SIGNON on the TYPE or TERMINAL macro.

SPECIFIC

Specifies that individual static terminals might be required to sign on. These terminals are specified in system definition with the OPTIONS=SIGNON parameter. SPECIFIC is the default.

SIGNTCO=

Specifies a user ID that IMS can use for transaction and command authority checking when a TCO terminal does not sign on. The user ID must be defined in RACF or a similar security product.

When the SIGNTCO parameter is used, IMS sets TCORACF to Y automatically. The TCO LTERM is signed on and the user ID is included in IMS log records.

If the SIGNTCO is not used and no /SIGN command was issued, then the control region user ID is used for authorization checking.

SLU2=EXR | NOEXR

Specifies whether all IMS-defined SLU2 terminals should be treated as with or without DFT architecture.

EXR

Specifies that all IMS-defined SLU2 terminals are treated as with DFT architecture. EXR is the default.

NOEXR

Suppresses the SNA exception response that proceeds an IMS error message. As a result of no exception response, the terminal PROG check is prevented, the keyboard is locked, and IMS is allowed to send the error message.

Requirement: Changing this parameter after a previous IMS start does not require a cold start. You must perform a warm start, however, to allow the new specification to take effect.

SMTO=name1 | (name1) | (name1,name2)

name1 specifies the node name of the secondary master terminal (SMTO). This name overrides the SMTO node name that is specified during IMS system definition.

name2 specifies the name of the additional SMTO resource that exists in an XRF environment. If name2 is specified in a non-XRF environment, it is ignored.

If the PMTO parameter is not specified, the default SMTO name (either one or both) that was specified during IMS system definition is used.

Requirement: Changing this parameter after a previous IMS start requires a cold start to take effect.

SMTOUSID=userid

Specifies a user ID that IMS will use if the secondary MTO does not sign on for transaction authorization checking.

SMTO1-8=name | (name) | (name,MASTER)

Specifies the first through the eighth LTERM names of the SMTO. The names you specify here override the first through the eighth LTERM names specified during IMS system definition. The LTERM name specified with the SECONDARY designation becomes the SMTO LTERM. These LTERM names must be unique for each IMS system within a shared IMS environment.

Requirement: Changing this parameter after a previous IMS start requires a cold start to take effect.

SMTOG=DFSSMTO | name

Specifies the generic LTERM name for the secondary master terminal. The default generic SMTO LTERM name is DFSSMTO. Use the same generic LTERM name for all IMS systems within a shared IMS environment.

Requirement: Changing this parameter after a previous IMS start requires a cold start to take effect.

SRMDEF=

Specifies the status recovery mode for user and node resources. Valid values are GLOBAL, LOCAL, and NONE.

Related reading: In order to understand completely what the GLOBAL, LOCAL, and NONE values mean, you have to first understand how IMS classifies resource status. For a discussion of these concepts, see IMS Version 13 System Administration.

The default value of SRMDEF depends on the operating environment:

• GLOBAL is the default if a resource structure and shared queues are used.
• LOCAL is the default if a resource structure and shared queues are not used.

The following list describes the valid values for SRMDEF.

GLOBAL

The significant status of a resource is saved globally in the coupling facility resource structure every time the significant status changes, along with all other recoverable status for that resource. The resource status is restored at the next logon or sign on and is available from any IMS system in the IMSplex. Resource status is copied to the local system when that resource becomes active, but is deleted from the local system when it becomes inactive. Status is not recovered in local IMS log records.

Requirement: Using a status recovery mode of GLOBAL requires a Resource Manager and a resource structure in the coupling facility. If STM=NO is specified, SRMDEF=GLOBAL is invalid.

LOCAL

The significant status is saved in local control blocks and log records, along with all other recoverable resource status. The resource status is restored at the next logon or sign on if the user or node returns to the same local IMS system. This status is not available on any other IMS system in the IMSplex.

LOCAL mode enforces an affinity for the user or node to the IMS system where the local status exists. This is referred to as RM affinity. IMS prevents the user or node from accessing any other IMS while local status exists. If the IMS system that has local status fails, the node and user are allowed access to another IMS system. In this case, the node or user does not recover any status and when the failed IMS restarts, the local status that existed is deleted.

Using a status recovery mode of LOCAL does not require a Resource Manager. If RM is not used to manage node or user resources, then no RM affinity is enforced.

NONE

The significant status is not saved by RM or in local log records. When the user signs on or the node logs on, the corresponding significant status does not exist.

STM=YES | N0

Specifies whether (YES) or not (NO) IMS is to use the RM resource structure to manage TM resources. The resources that are managed include APPC descriptors, VTAM LTERMS, MSNAMEs, VTAM terminal nodes, users, and user IDs. The default is YES.

A cold start is required if STM=NO is specified for installations that were previously using the resource structure.

Any change to the STM= specification requires a cold start of the TM component (COLDCOMM). This restriction is enforced during restart processing through the U233 ABENDU0233.

Note that transactions (both statically defined and CPI-C) are maintained in the resource structure independent of TM resources, regardless of the STM= specification.

If STM= is specified, but IMS is not using a resource structure, the specification is ignored.

TCOUSID=

Specifies a user ID that IMS can use for transaction and command authority checking when a TCO terminal does not sign on. The user ID must be defined in RACF or a similar security product.

When the TCOUSID= parameter is used, although IMS automatically sets TCORACF to Y, the TCO LTERM is not signed on and the user ID is not included in IMS log records.

If the TCOUSID= is not used and no /SIGN command was issued, then the control region user ID is used for authorization checking.

TRUNC=Y | N

Specifies the system default for the truncated data options used for IMS conversational transactions. If a transaction definition (TRANSACT) does not specify a truncated data option, the system default is used when a conversation starts for the first time.

Requirement: Changing this parameter after a previous IMS start does not require a cold start. You must perform a warm start, however, to allow the new specification to take effect.

VACBOPN=INIT | DELAY

Specifies that the opening of the IMS VTAM ACB is delayed until a /START DC command is issued. This parameter is optional. The following is an example of using the VACBOPN parameter.

• An IMS system is restarted (after an emergency restart) and this system includes many Automated Teller Machines (ATMs). All the ATMs attempt to connect immediately. The logon attempts are rejected by VTAM until IMS opens the VTAM ACB.

  If, however, the VTAM ACB is opened during initialization, VTAM begins queuing the logon requests. The programs in the ATMs wait for a short period of time for a response and then time out. When the timeout occurs, an UNBIND request is sent and this is also queued. This scenario continues until the logon is successful. Meanwhile, IMS has to complete its initialization and then process all the log records for the emergency restart.

  After the successful completion of the emergency restart, the operator can issue a /START DC command to tell VTAM to start accepting logon requests. When this finally happens, there are many UNBIND requests on the queue. At this point, the logon requests are queued behind enough error processing that they also time out.

  In some situations, apparently the IMS system is looping (because no sessions can get connected) and the operator is tempted to terminate IMS. Using the VACBOPN=DELAY parameter alleviates this problem by delaying the queuing of the logon requests until IMS is ready to start accepting the logon requests (when the /START DC command is issued).

INIT

Specifies that the IMS VTAM ACB is opened when IMS initializes.

DELAY

Specifies whether the IMS VTAM ACB is opened when a /START DC command is issued.

Requirement: Changing this parameter after a previous IMS start does not require a cold start. You must perform a warm start, however, to allow the new specification to take effect.

WTORUSID=

Specifies a user ID that IMS uses if the WTOR (system console) does not sign on for transaction authorization checking.

If you do not specify WTORUSID, the control region's user ID is used for any other terminal that does not sign on.

If both SIGNON=ALL and WTORUSID= are specified, the specification for WTORUSID= overrides the SIGNON=ALL specification for the system console.