PH53690: MQ Z/OS: ABEND0C4 IN CSQQWAIT CAN OCCUR WITH THE CSQQWAITSTIMER TUNING PARAMETER SET ON

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• When the customer is stopping an IMS dependent region, sometimes
  an ABEND0C4 or ABEND0C2 occurs in CSQQWAIT. This problem started
  when a service parameter that affects the mechanism used wait on
  TCBs in the IMS adapter code was turned on.
  
  The ABEND0C4 is in CSQQWAIT because WAU control block storage
  was freed during a 1-second STIMER wait interval that occurs
  with the parameter turned on.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 2 Modification 0 and                 *
  *                 Release 3 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: An 0C4 or an 0C2 abend is seen when an  *
  *                      IMS dependent region is stopped in      *
  *                      CSQQWAIT when a service parameter that  *
  *                      affects the mechanism used wait on TCBs *
  *                      in the IMS adapter code is turned on.   *
  ****************************************************************
  When stopping an IMS dependent region sometimes an 0C4 or 0C2
  abend occurs in CSQQWAIT when a service parameter that affects
  the mechanism used wait on TCBs in the IMS adapter code was
  turned on.
  
  The abends occur due to a timing window where the WAU control
  block storage was freed during a 1 second STIMER wait interval
  that occurs with the parameter turned on. After the STIMER ends
  an attempt to use the WAL/WAU storage is made resulting in
  either the 0C4 or 0C2 abend depending on the exact timings.
  

Problem conclusion

• The code has been updated to add defensive code to detect if the
  WAL has been freed during the STIMER call so that no attempt to
  access the storage is made if it has been found to be freed.
  

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:

  UI95919 UI95920

Modules/Macros

• CSQQTTHD CSQQWAIT
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R200 PSY UI95920

     UP24/03/19 P F403

• R300 PSY UI95919

     UP24/03/19 P F403

Fix is available

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