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PM83232: POTENTIAL OVERLAY BY CICS ON AN EXEC CICS READ FILE INTO LENGTH WHEN THE LENGTH IS BIGGER THAN THE RECORD BEING READ.

A fix is available

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APAR status

  • Closed as program error.

Error description

  • A program does an EXEC CICS READ FILE INTO LENGTH against
    a Recordformat(V) file.  The value specified for LENGTH is
    larger than there is room in the INTO area.  But the size
    of the record being read is small enough to fit within the
    INTO area.
       When that READ completes, LENGTH will be set to the size
    of the record and exactly that much data should be moved into
    the INTO area.  If that is what happens, then there is no
    problem since the INTO area is large enough for that.
       But there is a situation that causes CICS to move into the
    INTO more than the length of the record.  This happens when
    there is an exclusive control conflict.  The exclusive control
    conflict results in the task being briefly suspended.  But it
    should not affect the execution of the EXEC CICS READ at all.
    However, when an exclusive control conflict happens, the length
    of the data moved into the INTO area is equal to the LENGTH
    passed to CICS.
      For example:
    EXEC CICS READ FILE INTO LENGTH(32000)
    The FILE is RecordFormat(V).  The INTO area is large enough
    to hold 100 bytes.  The record being read is 100 bytes long.
    Normally, when that READ complete, CICS will set LENGTH to
    100 and will move that much data to the INTO area.  But when
    an exclusive control conflict happens during the processing of
    that READ, CICS will set LENGTH to 100 and will move 32000
    bytes to the INTO area.  That can cause a storage overlay.
    

Local fix

  • Make sure the LENGTH specified is not too large for the INTO
    area.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All CICS Users.                              *
    ****************************************************************
    * PROBLEM DESCRIPTION: EXEC CICS READ FILE INTO LENGTH can     *
    *                      lead to an overlay when the length      *
    *                      specified is bigger than the record     *
    *                      being read and the INTO area specified. *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    A program issues an EXEC CICS READ FILE INTO LENGTH command
    against a variable length record. If this record is locked
    by another task then this task will get an exclusive control
    conflict and will wait. Upon being woken up, it finds that
    it needs to retry the read. After the retry call to VSAM and
    knowing this is an INTO request, CICS needs to update the INTO
    area with the retrived record. When the INTO area is updated
    the length specified on the request is used rather than the
    length returned by VSAM. As the length is larger than the
    record and larger than the area provided by the INTO area an
    overlay occurs.
    

Problem conclusion

  • DFHFCVS has been updated to ensure that the length returned by
    VSAM is used to update the contents of the INTO area.
    

Temporary fix

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

Comments

APAR Information

  • APAR number

    PM83232

  • Reported component name

    CICS TS Z/OS V5

  • Reported component ID

    5655Y0400

  • Reported release

    800

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-02-20

  • Closed date

    2013-03-15

  • Last modified date

    2015-03-04

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

    PM79274

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

    UK92743

Modules/Macros

  • DFHFCVS
    

Fix information

  • Fixed component name

    CICS TS Z/OS V5

  • Fixed component ID

    5655Y0400

Applicable component levels

  • R800 PSY UK92743

       UP13/03/29 P F303

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:
04 March 2015