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OA36101: OVERLAY OF HIGH PRIVATE STORAGE WITH A UCB ADDRESS

A fix is available

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APAR status

  • Closed as program error.

Error description

  • A new dynamic allocation feature added in z/OS 1.12 is to
    suppress DD level accounting when the S99DASUP flag is set.
    When this bit is set, it will prevent DD entries from being
    added to the TCT I/O table (TCTIOT).
      The problem occurs when a data set is extended to a new
    volume.  In this case, the flag which indicates whether this DD
    has a TCTIOT entry is not checked and the TCTIOT is updated with
    the UCB address of the newly added volume.  Since the DD does
    not have a TCTIOT entry, an overlay will occur either within the
    TCTIOT itself or in the storage immediately following the
    TCTIOT depending on the location and size of the TCTIOT.
      In most cases, this occurs under DB2 with PM17542 applied
    since it exploits the S99DASUP option and results in an
    ABENDC78-54 when the PPD eyecatcher for the SIOTX cell pool is
    overlaid with a UCB address.
    
    Example of the overlay:
    - The TCTIOT (TCB+A4?+C?) in this example starts at x'7FFE60C0'.
    - The PPD eyecatcher (TCB+B4?+15C?+F4?+18?+10?+20?) should be at
      x'7FFE6160'.
    - Overlays occurred at 7FFE6120, 7FFE6140, and 7FFE6160
    
      7FFE60C0   FF000070   00000040   00000018   00000020
      7FFE60D0   0000002C   00000048   00000000   00000000
      7FFE60E0   022DCEE0   01007FF8   00002568   00002566
      7FFE60F0   00000000   00000000   00000000   00007FF8
      7FFE6100   00000000   00000000   00000000   01000000
      7FFE6110   00000000   00000000   00000000   00000000
      7FFE6120 ->022ACEE0   00000000   00000000   00000000
      7FFE6130   D3E2E2C4   01800000   00000000   00010002
      7FFE6140 ->022E8C40   7F6AA000   7FFE6150   00000000
      7FFE6150   00080000   7F6A1000   7F6A8000   00000000
      7FFE6160 ->022ACEE0   7F71E000   7FFE6198   00000021
      7FFE6170   00000042   00EC0064   007FF890   00000170
      7FFE6180   00003000   00005F00   00FC6A00   7FFE61D8
      7FFE6190   0000000C   00000000   E2D7C440   00000000
    
    Additional symptoms:
    - ABEND0C4 pic4 in IGVCPEXT during a cpool extend when the
      secondary cell count in the SIOTX PPD +x'10' is overlaid
      with a UCB address.
    
    Additional keywords:
    DSABDASP IEFAB4F7 ABENDC78 sC78 s0C78 rc54 rsn54
    

Local fix

  • A ++APAR is available.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All HBB7770 and above installations that     *
    *                 have applications that dynamically allocate  *
    *                 data sets using S99DASUP.                    *
    ****************************************************************
    * PROBLEM DESCRIPTION: When extending an SMS-managed data set  *
    *                      onto a new volume, a storage overlay    *
    *                      may result.                             *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    When a SMS-managed data set has a dynamic volume count,
    the system will automatically extend the data set onto
    additional volumes as appropriate.  However, when the data set
    was dynamically allocated using S99DASUP, which indicates that
    Allocation should suppress DD level accounting, then
    Allocation's processing to extend the data set onto an
    additional volume will erroneously attempt to update the DD
    entry in the TCT I/O table (TCTIOT.)  In this situation, there
    is no DD entry in the TCTIOT because DD level accounting has
    been suppressed.
    

Problem conclusion

  • Allocation processing to add or update a device in the TIOT is
    changed to check if there is a TCTIOT entry for the DD before
    attempting to update the TCTIOT entry for that DD.
    

Temporary fix

  • *********
    * HIPER *
    *********
    

Comments

APAR Information

  • APAR number

    OA36101

  • Reported component name

    ALLOCATION

  • Reported component ID

    5752SC1B4

  • Reported release

    770

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2011-04-04

  • Closed date

    2011-05-04

  • Last modified date

    2011-06-23

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

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

    UA60221 UA60222

Modules/Macros

  • IEFAB428
    

Fix information

  • Fixed component name

    ALLOCATION

  • Fixed component ID

    5752SC1B4

Applicable component levels

  • R770 PSY UA60221

       UP11/05/18 P F105

  • R780 PSY UA60222

       UP11/05/18 P F105

Fix is available

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Document information

More support for: z/OS family

Software version: 770

Operating system(s): MVS, z/OS

Reference #: OA36101

Modified date: 23 June 2011


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