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PK44403: SOS CONDITION ( BELOW THE LINE ) CAUSES CICS TO HANG DUE TO A CALL TO DFHAPDM TO TERMINATE DOMAINS FAILS FOR SMODE 24 STACK

A fix is available

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APAR status

  • Closed as program error.

Error description

  • The basic problem is that this region went SOS for UDSA
    because UDSA is fragmented so badly.  But then the CICS
    region got stuck there because the tasks started needing 1 4K
    page of below-the-line kernel stacks (KESTK24E) for various
    things but CDSA is also totally out of pages. So the tasks
    holding all of the UDSA couldn't move because they couldn't
    get below-the-line stack storage. But then they have DTIMOUT,
    so these tasks started getting abend AKEG after hanging for 1
    minute. Then that made the tasks want to put out a message
    (like DFHPG0001) to report that problem.  But one of the
    modules for putting out a message also needs an SMODE 24 stack.
    And so it hangs again and AKEG's again 60 seconds later. This
    repeats itself as the task percolates the slow-moving AKEG's
    back from stack to stack.  Eventually one of the tasks
    percolated an AKEG back to the DFHKETA stack level. But then
    there was an abend0C4 in DFHKETA (addressed in APAR PK39507 )
    because it assumes that there will be a prior stack.  Since
    there is no stack level to percolate that 0C4 error back to,
    DFHKERPC decides to bring CICS down with a KTCB_PERCOLATE_ERROR.
    But then the default QR KTCB task tries to call DFHAPDM to
    terminate domain, but that module needs a SMODE 24 stack and so
    the QR TCB just goes away and CICS is left there to hang.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All.                                         *
    ****************************************************************
    * PROBLEM DESCRIPTION: CICS went SOS in the UDSA and then      *
    *                      hung.                                   *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    In the reported problem, a CICS system was short of below the
    line storage and eventually hung.
                                                                   .
    UDSA was badly fragmented but various tasks were requesting
    4k pages of below the line kernel stack storage (KESTK24E)
    which was unable to be satisfied.
    
    The CDSA was fully allocated so below the line storage had been
    exhausted for CICS use.  The tasks eventually timed out with
    AKEG abends but in doing so, CICS attempted to issue DFHPG0001
    messages to report the problem. To do this, CICS module DFHKETI
    required below the line stack storage and CICS went into a
    permanent SOS condition.
    
    Keywords: short-on-storage msgDFHSM0131 DFHSM0131 SM0131 0131
    

Problem conclusion

  • DFHKETI now has SMODE 31 specified so that it will not require
    storage from the KESTK24E subpool.
    

Temporary fix

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

Comments

APAR Information

  • APAR number

    PK44403

  • Reported component name

    CICSTS 3.X Z/OS

  • Reported component ID

    5655M1500

  • Reported release

    400

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2007-05-03

  • Closed date

    2007-06-07

  • Last modified date

    2007-07-09

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

    PK39513

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

    UK25848 PK48557

Modules/Macros

  •    DFHKETI
    

Fix information

  • Fixed component name

    CICSTS 3.X Z/OS

  • Fixed component ID

    5655M1500

Applicable component levels

  • R400 PSY UK25848

       UP07/06/12 P F706

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.

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Document Information

Modified date:
09 July 2007