PM81545: IMS DISPLAY OF CICS THREADS SHOWS 1 THREAD WITH A STATUS OF UNAVAIL . A THREAD IN THAT STATE PREVENTS NORMAL IMS SHUTDOWN.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• With CICS/TS 5.1, there is a thread on an IMS display
  that has a status of UNAVAIL.  Here is an example of the
  display and the output:
  .
  /dis cctl cics1234
  .
  DFS4444I DISPLAY FROM ID=IMS1
  CCTL     PSEUDO-RTKN RECOVERY-TOKEN   REGID PSBNAME STATUS
  CI1FSAF1                                            ATTACHED
                    0000000000000000    16            AVAILABLE
                    0000000000000000    13            AVAILABLE
                    0000000000000000     5            AVAILABLE
                    0000000000000000     4            AVAILABLE
                    0000000000000000    18            AVAILABLE
                    0000000000000000     3            UNAVAIL
  .
  The last thread shows a status of UNAVAIL.  This status of
  UNAVAIL should be a very transient such that you would never
  catch a thread in that state on a display.  But this thread is
  staying with a state of UNAVAIL for long periods of time.
  .
  Also, IMS will not shutdown normally while a thread is in this
  state.  The thread must be stopped with a " STO REGION ABDUMP "
  before IMS can shutdown normally.
  .
  This problem happens for a thread that is associated with a
  long-running task in CICS.  This task does IMS requests, then
  does an EXEC CICS SYNCPOINT, then suspends for several seconds,
  and then repeats that sequence over and over for the entire
  run of CICS.  During the processing of the SYNCPOINT, CICS
  is calling IMS for SYNC TERM, but CICS is not calling IMS
  for TERMINATE THREAD.  Since CICS did not call IMS for
  TERMINATE THREAD, that is the thread has the UNAVAIL status.
  .
  Here are trace entries of EXEC CICS SYNCPOINT showing the
  problem *not* happening:
  .
  ERMSP ENTRY SEND_DO_COMMIT
  ERM   ENTRY SYNCPOINT-MANAGER-CALL-TO-TRUE(DBCTL   )
  ...
  DBAT  EVENT ABOUT-TO-INVOKE-DRA   FOR THREAD REQUEST ,...,030A
  ...
  DBAT  EVENT RECEIVES-CONTROL-FROM-DRA FOR THREAD REQUEST ,
  DBAT  EVENT ABOUT-TO-INVOKE-DRA   FOR THREAD REQUEST ,...,030F
  ...
  DBAT  EVENT RECEIVES-CONTROL-FROM-DRA FOR THREAD REQUEST ,
  ...
  ERM   EXIT  SYNCPOINT-MANAGER-CALL-TO-TRUE(DBCTL   )
  .
  The call to the DRA for 030F is the Terminate Thread.
  .
  Here is the trace of an EXEC CICS SYNCPOINT when the problem
  *is* happening:
  .ERMSP ENTRY SEND_DO_COMMIT
  ERM   ENTRY SYNCPOINT-MANAGER-CALL-TO-TRUE(DBCTL   )
  ...
  DBAT  EVENT ABOUT-TO-INVOKE-DRA   FOR THREAD REQUEST ,...,030A
  ...
  DBAT  EVENT RECEIVES-CONTROL-FROM-DRA FOR THREAD REQUEST ,
  ...
  ERM   EXIT  SYNCPOINT-MANAGER-CALL-TO-TRUE(DBCTL   )
  ERMSP EXIT  SEND_DO_COMMIT/OK     YES,YES,DBCTL
  .
  In this sequence, there is no call to IMS for Terminate Thread.
  That leaves this thread in a status of UNAVAIL.
  .
  What makes this behave one way or the other depends on the
  prior disconnection from IMS during this run of CICS.  If the
  prior disconnection from IMS was an Immediate disconnect, then
  after reconnecting with IMS, the problem will happen because
  the DGB field DGBDISTY (DGB +X'D9') is residually left set to
  X'02' ( DGBIMMDI ) which means Immediate Disconnect in progress.
  (Note there is no disconnect currently in progress. But that
  indicator is left on even after the Immdiate Disconnect
  completes and then the connection to IMS is re-established.
  .
  Following a normal disconnect from IMS, and then re-connect to
  IMS, DGB field DGBDISTY is residually left set to X'01'
  ( DGBORDDI ) which means Orderly Disconnect.  When that is the
  case, the problem does not happen.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: CICS users also using IMS.                   *
  ****************************************************************
  * PROBLEM DESCRIPTION: CICS IMS thread has status of UNAVAIL.  *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  While processing a CICS SYNCPOINT, CICS issued SYNC TERM to IMS,
  but did not also issue a TERMINATE THREAD command. The IMS
  thread representing the connection to the CICS region was not
  released, and remained in an UNAVAIL status after the CICS
  SYNCPOINT had completed.
  A CICS end of task SYNCPOINT should have issued a TERMINATE
  THREAD to IMS, but this was a long running task that did not
  end. It was necessary to issue STO REGION ABDUMP to terminate
  the thread and allow IMS to shutdown normally.
  The problem was caused because an earlier IMMEDIATE DISCONNECT
  request from CICS to IMS had set the value of DGBDISTY for this
  connection to DGBIMMDI. This setting was not cleared when the
  connection was reestablished.
  

Problem conclusion

• DFHDBCON has been corrected to clear the value of DGBDISTY when
  establishing a new connection to IMS.
  

Temporary fix

• FIX AVAILABLE BY PTF ONLY
  

Comments

APAR Information

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

  PM77996

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

  UK91763

Modules/Macros

• DFHDBCON
  

Fix information

• Fixed component name

  CICS TS Z/OS V5

• Fixed component ID

  5655Y0400

Applicable component levels

• R800 PSY UK91763

     UP13/02/28 P F302

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.