PI90544: MQ: ABN=5C6-00940001 AND CSQX206E DUE TO INVALID SEQUENCE OF XA FLOWS FROM CLIENT. 17/11/30 PTF PECHANGE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• abd 5c6 and CSQX206E caused by the XA client sending an invalid
  sequence of flows.
  
  The client is sending:
  
  xa_end() with TMFAIL
  
  followed by:
  
  xa_end() with TMSUCCESS
  
  This is invalid (for the same XID) as after the TMFAIL, the
  specification states that this:
  
  "dissociates caller and marks transaction branch rollback-only"
  
  However, despite this combination being invalid, MQ is not
  handling the exception in a graceful manner and that is why the
  abend is occurring.
  

Local fix

• investigate the client application to determine the incorrect
  sequence of xa calls
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 0 Modification 0                     *
  ****************************************************************
  * PROBLEM DESCRIPTION: Issuing multiple XA_END calls for the   *
  *                      same MQ XA transaction with the         *
  *                      CSQSERVICE1 flag set, results in abend  *
  *                      5C6-00940001 in CSQMCPRH.               *
  ****************************************************************
  With CSQSERVICE1, XA transactions can be prepared on a different
  client connection. However with this, when a XA_END call is made
  sucessfully, subsequent XA_END calls for the same XID result in
  abend 5C6-00940001 in CSQMCPRH, as the logic cannot find an XTE
  associated with the connection ACE. This also results in the
  subsequent XA_END calls for the XID failing unexpectedly with
  XAER_RMERR (-3).
  

Problem conclusion

• XA_END processing has been altered, to correctly handle the case
  where there is no associated XTE, and ensure the correct reason
  code, XAER_PROTO is returned on the subsequent XA_END call. In
  this case the QMGR should no longer abend.
  

Temporary fix

Comments

APAR Information

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

  PI89764

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

  UI52281

Modules/Macros

• CMQXRSRV CSQ7CBMC CSQMCALH CSQMCLMT CSQMCPRH CSQMDALL CSQMDCOH
  CSQMGETV CSQMXARH CSQMXCLN CSQXADPM
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R000 PSY UI52281

     UP17/12/16 P F712 {

Fix is available

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