PM22199: LOOP IN DFHMQIG CONNECTING TO MQ DURING CICS STARTUP

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Your CICS region hung during startup without connecting to MQ.
  Last messages were:
  .
  DFHSI8440I Initiating connection to MQ.
  DFHMQ0336 I CONNECT received from a PLT program.
  .
  There were no further startup messages and CICS was recycled to
  resolve the problem. The dump shows that the CPLT task was
  looping on an L8 TCB. Kernel stacks show that control was in
  module DFHMQIG, proc SELECT_QMGR. PSWs from MVS system trace
  show that the loop is within the XCF_LOOP routine in DFHMQIG.
  DFHMQIG is trying to select a queue manager to connect to but
  falls into a loop when the eligible queue manager on the same
  LPAR is not active or available.
  .
  Additional Symptom(s) Search Keyword(s):
  KIXREVSVR  Hang hangs hung loops IXCQUERY QUAMSYS SMCASID xIndex
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS Users                               *
  ****************************************************************
  * PROBLEM DESCRIPTION: An attempt to connect to a WMQ Queue    *
  *                      Sharing Group may cause CICS to hang if *
  *                      all the queue managers in the Queue     *
  *                      Sharing Group are inactive.             *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  A infinite loop happens in XCF_LOOP in DFHMQIG. XCF_LOOP is in
  proc select_qmgr. This has been called from
  choose_qmgr_from_csg after the call to the queue sharing group.
  This call will come back with a list of available queue managers
  in a buffer. The code in select_qmgr is intended to obtain the
  name of a qmgr this CICS region can connect to. Before we enter
  the XCF_LOOP we do a randomised search algorithm which
  will provide a starting point in the buffer and the direction to
  go through the buffer. The problem happens if this randomised
  algorithm provides the following combinations and no qmgrs are
  available to connect to. If it selects the first member and
  direction is forwards, or it selects the last member and the
  direction is backwards. In this case the exit decision code in
  the XCF_LOOP never gets triggered because we never get the
  condition which would enable it to do so.
  

Problem conclusion

• DFHMQIG has been changed to move the exit decision
  code to end of the loop in order to allow the end
  condition to be satisfied.
  

Temporary fix

• FIX AVAILABLE BY PTF ONLY
  

Comments

APAR Information

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

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

  UK61747

Modules/Macros

•    DESMQIG  DFHMQIG
  

Fix information

• Fixed component name

  CICS TS Z/OS V4

• Fixed component ID

  5655S9700

Applicable component levels

• R600 PSY UK61747

     UP10/11/03 P F011

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.