OA43255: PACE DEPENDENT LU SUPPORT GIVEBACK COMMANDS (DLUS/DLUR)

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• V NET,INACT,GIVEBACK commands using wildcards for the ID
  operand generate unpredictable amounts of work to VTAM.  For
  this reason, a new function will be created to internally pace
  the work generated by the GIVEBACK commands.
  

Local fix

• Use more restrictive wildcard names to keep the number of
  GIVEBACK operations to a reasonable value.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All using DLUR / DLUS.                       *
  ****************************************************************
  * PROBLEM DESCRIPTION: New function to pace                    *
  *                      V NET,INACT,TYPE=GIVEBACK processing    *
  *                      for dependent LU requestors (DLURs)     *
  *                      when wildcard names are in use.         *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  1) Environment consists of Enterprise Extender (EE) with
     thousands of EE endpoints.
  2) Each EE endpoint contains DLUR resources requiring
     DLUS support from a z/OS CS network node.
  3) Operator uses VARY INACT,TYPE=GIVEBACK commands
     with wildcard names specified for the ID operand.
  4) In this environment, the wildcard ID value may match
     1000s of DLUR names.  Internally, VTAM generates
     and immediately starts processing 1000s of
     GIVEBACK subcommands.
  5) The large number of subcommands generated by this
     wildcard operation causes a spike in network activity.
     This potentially puts a strain on network resources,
     prolonging searches because the subcommands are all processed
     immediately.
  6) A new VTAM start option (GVBKDLY) has been implemented to
     enable a new GIVEBACK delay function, which is disabled by
     default.  The new option allows VTAM to more efficiently
     process the work by adding small delays between the
     scheduling of batches of GIVEBACKs.
  7) When the last GIVEBACK subcommand (which is associated
     with the operator initiated DLUR GIVEBACK command)
     is scheduled for processing, new message IST2416I is
     issued back to the operator.
  

Problem conclusion

Temporary fix

Comments

• The following documentation changes have been made:
  
  z/OS IBM Communications Server
  SNA Resource Definition Reference
  Chapter 4. Start options
  Summary of start options
  
  1. Add the following description of new start option GVBKDLY
  to Table 62.
  
  Table 62. Start options that define APPN characteristics.
  
  GVBKDLY         The GVBKDLY start option determines whether
                  VTAM internally paces the subcommands generated
                  from a VARY INACT,TYPE=GIVEBACK command. This
                  start option affects GIVEBACK commands which use
                  wildcard values for the ID operand to deactivate
                  dependent LU requesters (DLURs).
  
  2. Add the following description of new start option GVBKDLY
  to Table 64.
  
  Table 64. Start options that define HPR and Enterprise Extender
  
  GVBKDLY         The GVBKDLY start option determines whether
                  VTAM internally paces the subcommands generated
                  from a VARY INACT,TYPE=GIVEBACK command. This
                  start option affects GIVEBACK commands which use
                  wildcard values for the ID operand to deactivate
                  dependent LU requesters (DLURs).
  
  3. Add description of new start option GVBKDLY
  Chapter 4. Start options
  Description of start options
  
  
      |-GVBKDLY=NO------------|
      |                       |
   >>-+---------------------------------------------------------><
      |                       |
      |-GVBKDLY=__ __NO____ __|
                  |__YES___|
  
  
  This option determines whether VTAM internally paces the
  GIVEBACK subcommands (GIVEBACKs) generated from a
  VARY INACT,TYPE=GIVEBACK command. The GVBKDLY start option
  only affects GIVEBACK commands which use wildcard values for
  the ID operand to deactivate dependent LU requesters (DLURs).
  Specifying GVBKDLY=YES causes VTAM to add internal delays to
  the scheduling of the GIVEBACK subcommands, resulting in more
  efficient processing when the wildcard value for the ID operand
  on a VARY INACT,TYPE=GIVEBACK command matches a large number of
  DLURs.  This start option is modifiable.
  
  NOTE: The use of wildcard values on GIVEBACK commands
        is controlled by the value of the VARYWLD start option.
  
  GVBKDLY = NO
  
    This specifies that VTAM will not internally pace the
    GIVEBACK subcommands generated from a
    VARY INACT,TYPE=GIVEBACK command.
  
  GVBKDLY = YES
  
    This specifies that VTAM will internally pace the
    GIVEBACK subcommands generated from a
    VARY INACT,TYPE=GIVEBACK command. The GVBKDLY start option
    only affects GIVEBACK commands which use wildcard values for
    the ID operand to deactivate dependent LU requesters (DLURs).
  
    Hint:    VTAM issues message IST2416I after it schedules the
             last GIVEBACK generated from the previous command.
             If there are multiple wildcard patterns to use for
             the VARY INACT command, wait until the IST2416I
             message is displayed before issuing another
             VARY INACT,TYPE=GIVEBACK command with a different
             wildcard pattern.
  
  
  z/OS IBM Communications Server
  SNA Operation
  Chapter 2. VTAM Operator command
  
  
  4. Add GVBKDLY to the Display VTAMOPTS
     (Function=APPNCHAR output)
  
  Display VTAMOPTS command
  
  FUNCTION=APPNCHAR
  
  Add GVBKDLY alphabetically in the defined start options
  associated with the APPNCHAR function list.
  
  5. Add GVBKDLY to the Display VTAMOPTS (Function=HPREE output)
  
  Display VTAMOPTS command
  
  FUNCTION=HPREE
  
  Add GVBKDLY alphabetically in the defined start options
  associated with the HPREE function list.
  
  6. Add GVBKDLY to the Modify VTAMOPTS railroad tracks
  
    >-+-----------------------+--------------------------------->
      |                       |
      |-GVBKDLY=__ __NO____ __|
                  |__YES___|
  
  7. Add GVBKDLY to the START command railroad tracks
  
  START command
  
      |-GVBKDLY=NO------------|
      |                       |
    >-+--------------------------------------------------------->
      |                       |
      |-GVBKDLY=__ __NO____ __|
                  |__YES___|
  
  
  8. Add Note (2) as follows under VARY INACT command
  
  VARY INACT command
  
  
  Deactivate a dependent LU requester (DLUR):
  
  
  
                                       (1)(2)_,FINAL=NO________
     >>__VARY NET,INACT__,ID=dlur_name______|__________________|_>
                                            |_,FINAL=_ _NO__ __|
                                                      |_YES_|
  
  
     >__ ______________________ ________________________________><
        |_,TYPE=_ _FORCE____ __|
                 |_GIVEBACK_|
                 |_IMMED____|
                 |_UNCOND___|
  
     Notes:
     (1)  Depending on the value of the VARYWLD start option,
          wildcard values can be used for this operand.
     (2)  Depending on the value of the GVBKDLY start option,
          GIVEBACK commands generated for DLURs using
          wildcard values may be paced by VTAM.
  
  
  z/OS IBM Communications Server
  SNA Messages
  
  IST2416I count type PROCESSED
  
  Explanation: Message IST2416I is issued once in response to a
  VARY INACT,TYPE=GIVEBACK command where wildcard values are used
  for the ID operand to specify which dependent LU requesters
  (DLURs) are to be deactivated.  This message is issued only
  when the GVBKDLY and VARYWLD start options are both enabled.
  
  In the message text:
  
  count is the number of resources processed by the command.
  
  type is based on the INACT command that was issued.  Possible
       values are:
  
       GIVEBACKS
  
          VARY INACT,TYPE=GIVEBACK processing for DLURs was
          performed
  

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  OA43382 UA70855

Modules/Macros

• ISTATCVT ISTCFCML ISTCFCMM ISTCICOM ISTCICPP
  ISTCICS2 ISTINCNO ISTNCSPL ISTNOCVI ISTTSCWU ISTVTMEU IST1050C
  IST2400C MSG2400
  

Fix information

• Fixed component name

  VTAM V4 MVS/ESA

• Fixed component ID

  569511701

Applicable component levels

• R1D0 PSY UA70855

     UP13/11/02 P F311

Fix is available

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