PK42184: QR TCB CAN HANG IN JES DURING JOB SUBMISSION THROUGH A WRITEQ TD TO AN EXTRAPARTION QUEUE WHOSE DD SPECIFIES SYSOUT=(A,INTRDR)

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Starting at z/OS 1.7, the work of submitting a job to JES
  through the INTRDR happens syncronously.  The requestor's TCB
  performs part of the work and it also hangs while a TCB in the
  JES2 address space performs part of the work.  The length of
  the hang can become significant as part of the work requires
  coordination with other JES2s in the Sysplex.
      Within CICS, the requester TCB is the QR TCB.  So it is now
  possible for the QR TCB to hang outside of the CICS dispatcher
  for a potentially long time while a task is using WRITEQ TD to
  write JCL to JES through the internal reader ( INTRDR ).
     When this happens, other tasks in CICS which need the QR TCB
  will spend lots of time waiting for redispatch on the QR.
  Additional Keywords:    QRMODDLY DISPWTT kixdcfzos17
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All.                                         *
  ****************************************************************
  * PROBLEM DESCRIPTION: Performance issues submitting work to   *
  *                      JES via INTRDR at z/OS 1.7 or higher.   *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  In the reported problem, work was submitted from CICS to JES on
  z/OS 1.7 via an EXEC CICS WRITEQ TD(TDQ) where the TDQ was an
  extrapartition transient data queue whose DD card specified
  SYSOUT=(x,INTRDR).  Prior to z/OS 1.7, the request would have
  been processed asynchronously by a JES TCB.  But at 1.7, the
  request was done synchronously using the submittors TCB (the QR)
  JES was unable to process the request expeditiously and tasks
  backed up in CICS waiting for the QR TCB.
  
  Keywords: DCTSDSBR RECORDFORMAT FIXED BLOCKFORMAT UNBLOCKED
            EXTRA_PUT_F
  

Problem conclusion

• DFHTDP has been modified. For fixed unblocked extrapartition
  transient data queues, a switch to the FO TCB will be made.
  
  The CICS Transaction Server for z/OS CICS System
  Definition Guide (SC34-6428-04) will be updated thus:
  
  Table 17 will be updated by the inclusion of SIT parameter
   ,TDSUBTASK={OFF|ON}
               ---
  
  A description of TDSUBTASK will be added to the section titled:
  'The system initialization parameter descriptions' thus:
  
  TDSUBTASK=(OFF|ON)
             ---
   Specifies whether CICS will use the FO TCB for writes to
   an extrapartition transient data queue whose recordformat
   is FIXED and blockformat is UNBLOCKED.
   The default is OFF meaning no TCB switch will occur.
  
    Note: This would particularly benefit those submitting work
          to JES via INTRDR at z/OS 1.7 or higher.
  
   Table 25 (the default system initialization table) will also
   be updated thus:
  
   Parameter       Default value     Description
   TDSUBTASK       OFF               No TD subtasking
  

Temporary fix

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

Comments

APAR Information

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

  PK40496

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

  UK25148 PK48550

Modules/Macros

•    DESTDA   DESTDEXP DFHPASY  DFHSIT   DFHSIT$$
  DFHSITPS DFHSIT6$ DFHTDA   DFHTDEXC
  

Fix information

• Fixed component name

  CICSTS 3.1 Z/OS

• Fixed component ID

  5655M1500

Applicable component levels

• R400 PSY UK25148

     UP07/05/22 P F705

Fix is available

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