PM70815: IF IMS EXTERNAL TRACE DATASETS ARE DEFINED WITH PRE IMS V9 MINIMUM BLKSIZE OF 4004, DATASET WILL BE MADE UNUSEABLE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• WHEN USING IMS v12, IF EXTERNAL TRACE DATASETS ARE DEFINED WITH
  BLKSIZE OF 4004 ( PRE IMS v9 MINIMUM BLKSIZE ) THE DATASET WILL
  BE MADE UNUSABLE AS FOLLOWS:
  .
  1. DEFINE EXTERNAL TRACE DATASETS DFSTRA01 / DFSTRA02 WITH
     LRECL=4004 AND BLKSIZE=4008
  2. ISSUE COMMAND : /TRACE SET ON TABLE DISP OPTION LOG
  3. NO ERROR MESSAGE. DCB NOW SET TO LRECL=4016 + BLKSIZE=4008
     LRECL IS GREATER THAN BLKSIZE, DATASET NOT USEABLE
  

Local fix

• DEFINE EXTERNAL TRACE DATASETS WITH CORRECT LRECL AND BLKSIZE
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:   All IMS V10 users of external              *
  *                   trace.                                     *
  ****************************************************************
  * PROBLEM DESCRIPTION:   IMS does not detect external          *
  *                        trace datasets with an invalid        *
  *                        block size.                           *
  ****************************************************************
  * RECOMMENDATION: INSTALL CORRECTIVE SERVICE FOR APAR/PTF      *
  ****************************************************************
      IMS does not detect external trace datasets that have
    an invalid block size.  This can occur if a user brings up
    IMS with external trace datasets that were allocated before
    IMS 9 when the LRECL was increased from 4004 to 4016.
  
      If a customer has their external trace datasets allocated
    with a LRECL of 4004 and a block size of 4008 and IMS
    attempts to use these datasets, the LRECL is changed to
    4016 but the block size remains at 4008.  IMS does not
    detect the problem, but the datasets are unusable.
  

Problem conclusion

• GEN:
  KEYWORDS:
  
  *** END IMS KEYWORDS ***
      The code in DFSTRA40 that checks to ensure the block
    is at least the LRECL+4 (4020) is comparing against a
    value of zero instead of 4020.
  
  
      IMS Module Changed
      ==================
  
      DFSTRA40
        The minimum block size check is modified to compare
        against the low half of the word that contains the
        minimum block size instead of the high half word.
  
  
    The following publication updates are made by this APAR:
  
  
    IMS Version 10: Messages and Codes, Volume 1:
                      DFS Messages
                    GC18-9712-00
  
    Modify the Explanation and System Action for the
    DFS2868W message as follows:
  
    Explanation:
      One of the external trace disk data sets has a block
      size smaller than the other data set or the block
      size is smaller than the minimum size.  Both external
      trace datasets should be the same size and specify
      block sizes of at least 4020.
  
    In the message text:
  
      nnnnnnnn
        The DD name of the external trace data set with
        the block size error.
  
    System Action:
      IMS will not use the external trace data set with the
      error.  If both data sets have errors, message DFS2867A
      is issued and the user can send the trace tables to
      the IMS log or keep them in storage.
  
  
  
    IMS Version 10: System Definition
                    ZES1-2916-00
  
    In chapter 13 (Setting up IMS for Diagnostics), change the
    LRECL and BLKSIZE descriptions for the external trace
    data sets.  This is under the section titled "Creating
    output data sets with correct attributes".
  
    For DFSTRA01 and DFSTRA02
  
    LRECL
        4016
  
    BLKSIZE
        The block size must be a multiple of the LRECL (4016)
        with an additional 4 bytes for the block descriptor
        work.  The formula (LRECL*N)+4 can be used to compute
        the block size.
  
        Recommendation:  Use a BLKSIZE of 20,084.  This is five
        logical records in length (4016 bytes, multiplied by 5)
        plus the block descriptor word (4 bytes)
  
    For DFSTRA0T
  
    LRECL
        4016
  
    BLKSIZE
        The block size must be a multiple of the LRECL (4016)
        with an additional 4 bytes for the block descriptor
        work.  The formula (LRECL*N)+4 can be used to compute
        the block size.
  

Temporary fix

Comments

APAR Information

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

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

  PM71297 PM71298 PM78533 UK90607

Modules/Macros

• DFSTRA40
  

Fix information

• Fixed component name

  IMS V10

• Fixed component ID

  5635A0100

Applicable component levels

• R010 PSY UK90607

     UP13/01/05 P F301

Fix is available

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