PH44258: MQ Z/OS: EOM PROCESSING HANGS FOR A CONNECTED JOB THAT WAS FORCED WHILE HOLDING AN MQ LATCH

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• After DB2 maintenance was applied, there was an attempt to
  restart related processes including IIB and MQ.  During the
  restart, two of the IIB processes did not terminate even with a
  z/OS CANCEL and FORCE. End Of Memory (EOM) processing did not
  complete. An IPL was required. A StandAlone Dump (SAD) was
  captured first.
  
  In the SAD, "SUMM FORMAT ASID(1)" showed several IEAVTMTR tasks
  attached to handle the EOM termination of the broker jobs.
  Each of these tasks was looping doing a WAIT every second from
  CSQ3RRSX (load module CSQ3EPX) in routine CCBDENDC_TEST waiting
  for DIEWA.lECB.
  
  The TCBs were waiting for an MQ service task TCB to do some
  work on their behalf. In this instance, the requests were made
  to the CRFMSR01 service task to do MQ security checks. There
  were multiple requests queued to this service task. The
  requests built up because the currently active request was
  suspended waiting for a MQ latch that was held by a TCB that
  had been forced.
  
  The force of the TCB meant that recovery would not run to
  release the latch, so the latch will be held indefinitely. This
  scenario usually results in QMGR termination.
  
  While it is expected that forcing address spaces connected to
  MQ might result in latches not being released, it is not
  expected that EOM processing will hang.
  

Local fix

• N/A.  An IPL is required
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 1 Modification 0 and                 *
  *                 Release 2 Modification 0 and                 *
  *                 Release 3 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: An RRS application undergoing a z/OS    *
  *                      Force or Memterm connected to MQ hangs  *
  *                      in EOM processing.                      *
  ****************************************************************
  An RRS application undergoing a z/OS Force or Memterm connected
  to MQ hangs during EOM processing under certain circumstances.
  
  The application must have a TCB waiting for a related TCB to
  complete that is doing work inside the QMGR on its behalf. The
  TCB in the QMGR is currently suspended on a latch it needs to
  obtain to complete its work.
  
  This latch must currently be held by a similar TCB by the same
  application. As the application is undergoing a z/OS Force or
  Memterm this latch will never be freed.
  
  The result is a hang in EOM processing as this hang occurs
  before the QMGR has a chance to process the EOM broadcast,
  detect that the application is undergoing a z/OS Force or
  Memterm and holds a latch in MQ to then issue the appropriate
  abend (6C6-00F3040A) and associated abnormal QMGR termination as
  expected.
  

Problem conclusion

• The code has been corrected to detect this scenario and break
  out of the hang allowing the QMGR to correctly process the EOM
  broadcast, detect that an application is undergoing a z/OS Force
  or Memterm and holds a latch in MQ.
  
  The correct abend for this scenario (6C6-00F3040A) and
  associated expected abnormal QMGR termination now occurs.
  

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:

  UI90452 UI90453 UI90455

Modules/Macros

• CSQ3RRSI CSQ3RRSM CSQ3RRSX CSQARIB
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R100 PSY UI90453

     UP23/03/08 P F303 ¢

• R200 PSY UI90452

     UP23/03/08 P F303 ¢

• R300 PSY UI90455

     UP23/03/08 P F303 ¢

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.