OA62381: A LOOP CAN OCCUR IN IEFVDBSD WHEN DSENQSHR IS SET TO ALLOW IN THE JOBLCASS

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• When DSENQSHR is set to ALLOW and the DSENQ table is full, a
  processing loop is entered that can be infinite if storage
  location 4 is zeroed out.
  
  ANALYSIS:
  Module IEFVDBSD is entered to create a new DSENQ table.  If
  DSENQSHR=ALLOW is specified and the current DSENQ table being
  looked at is full, a loop is entered that checks if the next
  entry to be added is a duplicate of an entry already in the
  table.  The fields used to iterate through the loop are
  incorrect and this can cause a situation where the loop counter
  is subtracted by zero each time through the loop if the storage
  at location x'00000004' is zeroed out.
  
  KNOWN IMPACT:
  Looping in IEFVDBSD in JES address spaces.
  High CPU usage in JES address spaces where job conversion is
  occurring.
  
  VERIFICATION STEPS:
  Verify that DSENQSHR is set to allow in the JOBCLASS and the
  loop is occurring in module IEFVDBSD.
  

Local fix

• BYPASS/CIRCUMVENTION:
  Set DSENQSHR to DISALLOW in the relevant JOBCLASSes
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * Installations running HBB77B0 or above                       *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * An endless loop may occur in the job interpreter while the   *
  * data set enqueue table is being processed.                   *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  When the DSENQSHR function is active for a job, endless loop
  conditions may occur in job interpreter processing. This is
  because the JCL interpreter uses incorrect loop control
  processing for searching the data set enqueue table for
  duplicate entries.
  
  Additional keywords: DSENQ DSNQ DSENQSHR=ALLOW DSENQSHR=AUTO
  

Problem conclusion

• Job interpreter loop processing for the data set enqueue table
  as described in this APAR is corrected.
  

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:

  UJ07703 UJ07704 UJ07705

Modules/Macros

• IEFVDBSD
  

Fix information

• Fixed component name

  CONVERTER/INTER

• Fixed component ID

  5752SC1B9

Applicable component levels

• R7D0 PSY UJ07705

     UP22/02/23 P F202

• R7C0 PSY UJ07704

     UP22/02/23 P F202

• R7B0 PSY UJ07703

     UP22/02/23 P F202

Fix is available

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