PI20312: DUMP TITLE=CSQ2,ABN=0C4-00000011,U=CICSTS ,C=R3600.710.CFM -CSQETHDP,M=CSQGFRCV,LOC=CSQELPLM.CSQETHDP

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• The customer was running WMQ V7.1 in a 3-way QSG with z/OS
  V2R1.  While running some of their MQCICS workloads using
  shared queues they lost full connectivity to CF21 in which some
  simplex structures resided.  They took a S0C4 dumps with one
  of the CICS regions.
  .
  IEA794I SVC DUMP HAS CAPTURED:
  DUMPID=025 REQUESTED BY JOB (IOSAS   )
  DUMP TITLE=COMPON=XES,COMPID=5752SCIXL,ISSUER=IXLM1REC,
             MODULE=IXLE1CRW,ABEND=S0026,REASON=07070001
  .
  +DFHDU0201 CICS3A2A ABOUT TO TAKE SDUMP. DUMPCODE: MQ0480  ,
  DUMPID: 1/0004
  .
  IEA794I SVC DUMP HAS CAPTURED:
  DUMPID=026 REQUESTED BY JOB (CICS3A2A)
  DUMP TITLE=CSQ2,ABN=0C4-00000011,U=CICSTS  ,C=R3600.710.CFM
  -CSQETHDP,M=CSQGFRCV,LOC=CSQELPLM.CSQETHDP
  .
  The change team reviewed the doc and the S026 abends appear to
  be linked to the 0C4 only in that they appear to relate to a
  loss of connection to the CF/structures, and the processing
  performed by MQ due to the connection loss led to the 0C4
  occurring. The S026 abends do not appear to be related to MQ -
  VERBX MTRACE shows errors involving paths being
  stopped/restarted - if these were not expected these dumps
  would need to be looked at by XCF to determine the reason for
  the S026-07070001 abends.
  .
  They have now been able to identify the cause of the 0C4 in
  CSQETHDP, which occurs when a structure failure or loss of
  connectivity to a structure occurs while an MQPUT1 is in the
  process of putting to a shared queue on that structure. While
  handling the connection loss, MQ incorrectly frees control
  blocks relating to the queue that are still required by the
  MQPUT1 processing, leading to the abend 0C4 when they are next
  referenced.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 7 *
  *                 Release 1 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Abend 0C4 occurs in CSQETHDP or         *
  *                      CSQMPOM if a structure fails or         *
  *                      connection to a structure is lost while *
  *                      a message is being put to the queue by  *
  *                      an MQPUT1 call or an internal put call. *
  *                      In some circumstances the abend is      *
  *                      followed by abnormal queue manager      *
  *                      termination S6C6 with REASON=00E50702   *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  During put processing for a shared queue, the queue manager
  detects that the structure containing the shared queue has
  failed, or lost connectivity to this queue manager. CSQISQC1 is
  called to decrement the uncommitted count for the queue and
  checks if the queue is currently in use. However in some cases,
  such as MQPUT1 calls or internal put calls, it can incorrectly
  determine that it is not in use. This causes the queue to be
  disconnected and the shared queue token to be freed.
  The abend occurs when put processing subsequently attempts to
  access the queue using the freed shared queue token.
  

Problem conclusion

• Put processing is changed to correctly indicate that it is using
  a shared queue in the affected cases, preventing the queue being
  disconnected and the shared queue token being freed until after
  the put operation has finished using the queue.
  100Y
  CSQESTFA
  CSQISQC1
  CSQMCLSQ
  CSQMCSQ1
  CSQMOSQ1
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

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

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

  UI20126

Modules/Macros

• CSQESTFA CSQISQC1 CSQMCLSQ CSQMCSQ1 CSQMOSQ1
  

Fix information

• Fixed component name

  WMQ Z/OS V7

• Fixed component ID

  5655R3600

Applicable component levels

• R100 PSY UI20126

     UP14/08/30 P F408 ¢

Fix is available

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