PH39461: IBM MQ Z/OS: REDUCE STORAGE CONTENTION FROM IXLCONN NOTIFYEXIT

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• MQ routine CSQENTFY is setup as a NOTIFYEXIT on IXLCONN
  connections to CF structures.
  
  It obtains a small amount of stack storage and then immediately
  frees it.
  
  If there is lots of CF structure lock contention, then this
  routine will be driven very frequently.
  
  The repeated freeing and releasing of storage should be reduced.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 1 Modification 0                     *
  *                 Release 2 Modification 0 and                 *
  *                 Release 3 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Repeated storage obtain/release seen    *
  *                      in systrace when there is contention    *
  *                      for a list lock in an application       *
  *                      structure.                              *
  ****************************************************************
  When a list lock is requested while already held by another
  task and/or queue manager, the MQ notify exit CSQENTFY is
  called.
  When significant contention for locks occurs, the many calls to
  CSQENTFY can result in the same area of storage being repeatedly
  obtained and released unnecessary.
  

Problem conclusion

• CSQENTFY is changed to remove the requirement to obtain and
  release the storage on each invocation.
  

Temporary fix

Comments

APAR Information

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

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

  UI81593 UI81594 UI81595

Modules/Macros

• CSQENTFY
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R100 PSY UI81595

     UP22/08/03 P F208

• R200 PSY UI81594

     UP22/08/03 P F208

• R300 PSY UI81593

     UP22/08/03 P F208

Fix is available

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