PI48783: READQ TD WITH UNDOCUMENTED EIBRCODE X'EF'

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Two interleaving CICS tasks are working with the same logically
  recoverable Transient Data (TD) queue. If task1 has written an
  uncommitted record to the queue, task 2 has to suspend on
  td_read to await the records to be committed. Task 1 does a
  rollback. Then task 2 is posted as expected and run into a
  delay. This allows task1 to write another record to the queue.
  When task 2 comes out of the delay, CICS tries to unlock the
  DCT again. This leads to unlock failure. In the CICS trace the
  following exception entry is recorded:
  .
  AP F621,TDB   *EXC* - Failed_to_unlock_DCTE - FUNCTION(UNLOCK)
  LOCK_TOKEN(5955A7F0) MODE(EXCLUSIVE)
  .
  

Local fix

• n/a
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All                                          *
  ****************************************************************
  * PROBLEM DESCRIPTION: EXEC CICS READQ command returns ERROR   *
  *                      when reading a logically recoverable    *
  *                      transient data queue.                   *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  A task has written to a logically recoverable transient data
  queue. Before it commits the written data, another task reads
  the queue. As the data is uncommitted, the second task suspends
  until the data is committed. DFHTDB releases the lock on the
  DCT entry before suspending the task. The first task abends and
  backs out the data it wrote to the queue. It then writes data
  back to the queue once more. When the second task is resumed,
  it sees that the queue still has uncommitted data and so has
  to suspend again to wait for this to be committed by the
  writing task. The cloop code in DFHTDB branches back to
  reissue the suspend. DFHTDB tries to unlock the DCT entry once
  more but the task no longer has the lock on the table and so
  the unlock fails. CICS issues exception trace entry AP F621
  (Failed_to_unlock_DCTE). It primes TDTD_RESPONSE to
  disaster. When the READQ completes, CICS returns the disaster
  to the API layer and EIP returns ERROR on the command.
  Keywords: TD APF621 TDB
  

Problem conclusion

• DFHTDB has been modified to reacquire the lock on the DCTE
  after the suspend has completed with an ok response. This
  allows the logic in the cloop routine to iterate back and
  release the lock validly before suspending once more if
  required.
  

Temporary fix

• FIX AVAILABLE BY PTF ONLY
  

Comments

APAR Information

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

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

  UI32879 PI54161 PI54162

Modules/Macros

• DFHTDB
  

Fix information

• Fixed component name

  CICS TS Z/OS V5

• Fixed component ID

  5655Y0400

Applicable component levels

• R900 PSY UI32879

     UP15/11/20 P F511

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.