Changing IGDSMSxx parameters to support the coupling facility

The SYS1.PARMLIB IGDSMSxx member includes several parameters that support the coupling facility. With the exception of RLSINIT, these parameters apply across all systems in the Parallel Sysplex®. The parameter values specified for the first system that was activated in the sysplex are used by all other systems in the sysplex.

The following SYS1.PARMLIB IGDSMSxx member parameters support VSAM RLS:

CF_TIME
DEADLOCK_DETECTION
RLSINIT
RLS_MaxCfFeatureLevel
RLS_MAX_POOL_SIZE
RlsAboveTheBarMaxPoolSize
RlsFixedPoolSize
SMF_TIME

You can change the values for these parameters during VSAM RLS processing only when all the spheres are closed . The new values are then used by all systems in the Parallel Sysplex, except for RLSINIT parameter values which are used only by the system accessing the changed parmlib member when SMSVSAM is next started.

To change the values of these parameters, use one of the following methods:

Issue the SETSMS operator command, specifying the parameter with different values.
Issue the T SMS=xx command, where xx identifies an IGDSMSxx member where the parameter values are different than those currently in use.

The following list describes the parameters and their values:

{CF_TIME(nnn|3600)}

Indicates the number of seconds between recording SMF type 42 records with subtypes 15, 16, 17, 18, and 19 for the CF (both cache and lock structures). You can specify a value from 1 to 86399 (23 hours, 59 minutes, 59 seconds). The default is 3600 (one hour).

This keyword sets the interval time for the following SMF 42 subtypes:

SUBTYPE 15: CF storage class average response time
SUBTYPE 16: CF data set average response time
SUBTYPE 17: CF lock structure activity
SUBTYPE 18: CF cache partition summary
SUBTYPE 19: SMSVSAM least recently used statistics summary

{DEADLOCK_DETECTION(iiii|15,kkkk|4)}

Specifies the deadlock detection intervals used by the Storage Management Locking Services.

iiii: specifies the length in seconds of the local deadlock detection interval, as a one to four digit numeric value in the range 1-9999. The default is 15 seconds.
kkkk: specifies the number of local deadlock cycles that must expire before global deadlock detection is run, as a one to four digit numeric value in the range 1-9999. The default is 4 cycles.

[RLSINIT({NO|YES})]

Specify YES if you want the SMSVSAM address space started as part of system initialization or the V SMS,SMSVSAM,ACTIVE command. This value applies only to the system accessed by the parmlib member and is acted upon when SMSVSAM is next started. The default is NO.

[RLS_MaxCfFeatureLevel({A|AMx|Z})]

Specifies the method that VSAM RLS uses to determine the size of the data that is placed in the CF cache structure.

If you specify A, caching proceeds using the RLSCFCACHE keyword characteristics that are specified in the SMS data class that is defined for the VSAM sphere.

With feature level A the user can also specify Mx values in the form of AMx to customize IGW500I messages for open spheres as follows:

M0: IGW500I messages for all open spheres will be suppressed.
M1: IGW500I messages for all open spheres will be displayed.
M2: Only for the first sphere opened in the sysplex will an IGW500I message be displayed.
M3: IGW500I messages for all open spheres in the sysplex will be sent to hardcopy.
M4: Only for the first sphere opened in the sysplex will an IGW500I message be sent to hardcopy.

If you do not specify a value, or if you specify Z, then only VSAM RLS data that have a Control Interval (CI) value of 4K or less are placed in the CF cache structure. The default is Z.

Restrictions: The restrictions are described below.

If A is specified for the RLS_MaxCfFeatureLevel parameter, systems lower than z/OS® V1R3 will not be able to connect to the CF cache structure.
If a lower-level system is the first system activated in the sysplex, RLS_MaxCfFeatureLevel defaults to Z, and all systems will be able to connect to the CF cache structure.
If the SETSMS command is used to change the RLS_MaxCfFeatureLevel value to A on a mixed-level system, the command is rejected and message IGW500I is issued.
The Mx modifier can only be combined with feature level A in the form of AMx, otherwise an IGW467I will be issued to indicate that the Parmlib value specified is not valid.
If the SETSMS command is used to change the RLS_MaxCfFeatureLevel value to Z when there are VSAM spheres assigned to cache structures, the command is rejected and message IGW500I is issued.

[RLS_MAX_POOL_SIZE({nnnn|100})]

Specifies the maximum size in megabytes of the SMSVSAM local buffer pool. SMSVSAM attempts to not exceed the buffer pool size you specify, although more storage might be temporarily used. Because SMSVSAM manages buffer pool space dynamically, this value does not set a static size for the buffer pool.

Use SMF 42, subtype 19 records to help you determine the maximum size of the SMSVSAM local buffer pool.

You can specify a two to four-digit numeric value, with 10 as the minimum value. If you specify a value less than 10, the field is set to 10. If you specify a value greater than 1500, SMSVSAM assumes there is no maximum limit. We recommend that you limit the size of the local buffer pool.

The default is 100 MB.

[RlsAboveTheBarMaxPoolSize{( sysname, maxrls; ...)|(ALL,maxrls}]

Specifies the maximum amount of virtual storage above the 2-gigabyte bar that can be used for VSAM RLS buffering in a system in the sysplex, where:

sysname identifies a system and maxrls is specified in megabytes for that system. Multiple sets of sysname, maxrls pairs may be specified, separated by semicolons.
(ALL,maxrls) specifies that each system in the sysplex will have the same specified value.

The default for maxrls is 0, and the specifiable values are 500 to 2000000 (that is, 500MB to 2 terabytes).

[RlsFixedPoolSize{( sysname, maxrls; ...)|(ALL,maxrls}]

Specifies the total amount of real storage (both above and below the 2-gigabyte bar) to be dedicated to VSAM RLS buffering in a system in the sysplex, where:

sysname identifies a system and maxrls is specified in megabytes for that system. Multiple sets of sysname, maxrls pairs may be specified, separated by semicolons.
(ALL,maxrls) specifies that each system in the sysplex will have the same specified value.

The default for maxrls is 0, and the specifiable values are from 0 to 80% of the total unpinned available real storage. When 80% is reached, the RLS address-space SMSVSAM Initialization will issue a message to warn of the limit.

[SMF_TIME({YES|NO})]

Specifies that the following SMF type 42 records are created at the SMF interval time, and that all of the indicated records are synchronized with SMF and RMF data intervals.

SUBTYPE 2: Cache control unit statistics (IBM® 3990-3, 3990-6, IBM RVA, and IBM ESS)
SUBTYPE 15: Coupling facility storage class average response time
SUBTYPE 16: Coupling facility data set average response time
SUBTYPE 17: Coupling facility lock structure activity
SUBTYPE 18: Coupling facility cache partition summary
SUBTYPE 19: SMSVSAM least recently used statistics summary

This allows the customer to merge these SMF records for a specified time period and obtain both the 'system' view and the 'user' view of activity in the interval.

YES is the default. DFSMS creates the specified SMF record when the interval period expires and SMF sends the event notification signal.

If you specify YES, SMF_TIME overrides the following IGDSMSxx parameters: CACHETIME, CF_TIME.