PM68981: REGION REMAINS IN STOPPING-FORCE CONNECTION STATUS AFTER STOP FORCE TO DISCONNECT FROM MQ

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• After an MQ crash CICS is trying to disconnect from MQ, however
  the connection status remains in Stopping-Force. There are a
  number of transactions currently active to MQ, and trying to
  execute MQ requests. As long as these tasks are still active the
  disconnect from MQ will not complete and will remain in the
  Stopping-Force state. x'7C' into the DFHMQLOC (CTTASKS) shows
  that there are currently a number of active CICS-MQ tasks. The
  disconnect will not complete until these tasks are resolved and
  purged.
  .
  Looking at those tasks it appears that these tasks were attached
  after a STOP FORCE was issued, so they could not be the reason
  that the STOP FORCE did not complete and why the connection is
  in the Stopping-Force status. New tasks should not be able to
  obtain an MQLOT and try to issue MQ requests because we are
  trying to disconnect at this point. So all new tasks should be
  abended when they try to do this In order for the disconnect to
  complete, the CTTASKS value has to reach 0. However, we are not
  reaching that value because we are still allowing new tasks to
  be attached and carry out MQ function, thus raising the CTTASKS
  value.
  .
  In addition, since the STOP FORCE is issued, all tasks currently
  in MQ are supposed to be forcepurged immiediately which would
  bring that CTTASKSvalue down to 0. However, we see in the trace
  that even after the STOP FORCE is issued, tasks are still
  issuing MQ requests and they are purged eventually, not
  immediately. So in essence we have a situation where:
  .
  - MQ crashes
  - CKAM issues STOP FORCE in order to disconnect then reconnect
    to MQ
  - Tasks that should have been purged for the STOP FORCE still
    run and issue MQ requests
  
  - New waves of tasks arrive and issue MQ requests that fail
    (these should have been abended and never allowed to get
    on the MQ task chain)
  - Tasks that were around when the STOP FORCE is issued are
    finally forcepurged
  - The New tasks continue to run and attempt MQ requests
  .
  So in this situation we will never get an CTTASKS value of 0 and
  in turn the disconnect will not complete and we will remain in
  the Stopping-Force status. Logic should be added to issue a
  connection status check prior to creating a new task LOT in
  order to prevent this kind of error.
  Additional Keywords: Forcepurge , Disconnect , Stopping , Force
  KIXREVSLY
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All                                          *
  ****************************************************************
  * PROBLEM DESCRIPTION: The CICS/WMQ adapter remains in an      *
  *                      indefinite "Stopping Force" state       *
  *                      after the WMQ address space abends.     *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  A WMQ Queue Manager address space abends S0C6, after which the
  CICS/WMQ adapter in a CICS region attached to the Queue Manager
  remains in a "Stopping Force" state indefinitely.
  Additional keywords: abends0c6 abend0c6 msgdfhmq0341 msgmq0341
  msg0341 mq0341
  

Problem conclusion

• DFHMQTRU has been modified so that new tasks entering the system
  when the CICS/WMQ adapter is not available are prevented from
  being added to the LOT chain and thus halting the successful
  shutdown of the adapter.
  

Temporary fix

•             *********
              * HIPER *
              *********
  FIX AVAILABLE BY PTF ONLY
  

Comments

• ž**** PE13/05/22 FIX IN ERROR. SEE APAR PM88203  FOR DESCRIPTION
  

APAR Information

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

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

  UK82953 UK82954

Modules/Macros

•    DFHMQTRU
  

Fix information

• Fixed component name

  CICS TS Z/OS V4

• Fixed component ID

  5655S9700

Applicable component levels

• R600 PSY UK82953

     UP12/11/03 P F211

• R700 PSY UK82954

     UP12/11/03 P F211

Fix is available

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