IBM Support

PI23781: CICS DOES NOT AUTOMATICALLY RECONNECT TO DB2 FOLLOWING A DB2 ABEND AND RESTART.

A fix is available

Subscribe

You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • CICS remains up while DB2 abends and restarts.  CICS does
    not automatically reconnect to DB2 as soon as DB2 is ready to
     accept connections.
        There are 2 possible symptoms: 1) CICS does automatically
     reconnect to DB2 eventually after several (less than 5)
    minutes.
     Or 2) CICS never automatically reconnects to DB2 and CICS
    issues
    a " DFHDS0001 AN ABEND (CODE 0C4/AKEA) HAS OCCURRED AT OFFSET
    X'40C6' IN MODULE DFHDSDS4. " less than 5 minutes after DB2
    was restarted.
       In a dump of CICS, either the DFHDS0001 0C4 in DFHDSDS4
    dump or a console dump while CICS hasn't yet reconnected to
    DB2, the 'DB2=1' summary shows the status of the DB2
    connection is Disconnecting and there are some transactions
    showing in the Transaction Summary.  Note those transaction
    numbers and then go to the 'DS=1' summary.
       In the DS=1 summary, you will find that those transaction
    
    numbers are either suspended or dispatchable on an L8 TCB.
    Go to the bottom of the DS=1 summary and note the MVS TCB for
    each of the transactions (from the DB2=1 summary) that are shown
    as Suspended or Dispatchable on an L8 (from the DS=1 summary).
    .
    Go to Summ Format.  You will find that those MVS TCBs are not
    in the address space.  They are gone, but their corresponding
    CICS transactions do not know that.  The CICS transactions are
    suspended or dispatchable on an MVS TCB that is gone.
    .
    KIXREVSWM
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All CICS users                               *
    ****************************************************************
    * PROBLEM DESCRIPTION: CICS never automatically reconnects     *
    *                      to DB2 and issues a " DFHDS0001 AN      *
    *                      ABEND (CODE 0C4/AKEA) HAS OCCURRED AT   *
    *                      OFFSET X'40C6' IN MODULE DFHDSDS4. "    *
    *                      message.                                *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    The 0c4 in DFHDSDS4 occurs if a transaction
    that has issued a DB2 call is in a CICS
    dispatcher wait, waiting on an ECB that is
    located in z/OS storage that is associated with the
    transactions open TCB.
    When DB2 crashes that ECB storage will be
    released when the TCB is deleted. When CICS attempts to
    terminate this CICS transaction it references the now
    non-existent ECB which causes an 0c4 to
    occur in DFHDSDS4. This 0c4 is not handled correctly
    which results in the CICS transaction hanging forever
    which prevents CICS reconnecting with DB2.
    Keywords: abend0C4 abendS0C4 0C4 S0C4
    

Problem conclusion

  • CICS has been changed so it now handles this 0c4
    correctly and prevents the transaction from hanging.
    CICS now schedules SMSY to execute immediately instead on
    waiting for the next scheduled slot.
    The CICS Transaction Server for z/OS Version 5 Release 1
    Diagnosis Reference GC34-2852-00 will be changed to add the
    following new exceptions to Chapter 83. Kernel Domain (KE)
    in the section "KEDS gate, FREE_TCBS function" :-
    "FREE_TCBS_LOCK_HELD
     TASK_NOT_TERMINATED"
    and a new section inserted before "KEDS gate, INQUIRE_MVSTCB
    function" :-
    "KEDS gate, FREE_TCBS_NOTIFY_IMMED function
     The FREE_TCBS_NOTIFY_IMMED function of the KEDS gate
     immediately notifies the Kernel system task that it needs to
     call function FREE_TCBS.
     Output Parameters
     RESPONSE
     Indicates whether the domain call was successful. For more
     information, see RESPONSE parameter on domain interfaces."
    The CICS Transaction Server for z/OS Version 5 Release 1
    Trace Entries SC34-2873-00 manual will be changed to add the
    following trace point to Chapter 19. Kernel domain trace points
    in Table 159 "Kernel domain trace points" :-
    "KE 050B  DFHKEDS  Exc   Notify error  1 KEDS parameter list
                                           2 TISR parameter list"
    

Temporary fix

  • FIX AVAILABLE BY PTF ONLY
    

Comments

APAR Information

  • APAR number

    PI23781

  • Reported component name

    CICS TS Z/OS V5

  • Reported component ID

    5655Y0400

  • Reported release

    800

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2014-08-13

  • Closed date

    2014-10-27

  • Last modified date

    2015-03-05

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

    PI17865

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

    UI22542 UI22543

Modules/Macros

  • DFHDPWB@
    

Publications Referenced
GC34285200SC34287300   

Fix information

  • Fixed component name

    CICS TS Z/OS V5

  • Fixed component ID

    5655Y0400

Applicable component levels

  • R800 PSY UI22542

       UP14/11/05 P F411

  • R803 PSY UI22543

       UP14/11/05 P F411

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.

[{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSGMGV","label":"CICS Transaction Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Line of Business":{"code":"LOB35","label":"Mainframe SW"}}]

Document Information

Modified date:
30 April 2020