PI23986: EMERGENCY RESTART OF CICS HANGS AFTER MESSAGE DFHLG0747I SYSTEM LOG SCAN CONTINUING, COUNT RECORDS PROCESSED.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• You have defined a recoverable ESDS file with no XFCLDEL exit
  active.  If a task tries to backout an ADD to the file then this
  will fail with message DFHFC4701, failure code x'40'. If this
  occurs for many thousands of tasks then this can lead to a
  region outage.  A subsequent emergency restart will attempt to
  reconstruct these units of work and rebuild their locks.  The
  last set of messages you see are: DFHLG0747I System log scan
  continuing, n,nnn,nnn records processed
  The large number of shared locks required against the FCT can
  result in another outage.
  .
  Additional Keywords: KIXREVACC UNLOCK_SHARED
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS users.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: CICS is unresponsive following the      *
  *                      accumulation of backout failures for    *
  *                      UOWs which performed write operations   *
  *                      to a VSAM ESDS.                         *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  CICS is required to back out a unit of work that performed a
  write operation to a recoverable VSAM ESDS.  However no XFCLDEL
  global user exit is enabled and started.  As a consequence a
  backout failure occurs and the UOW is shunted.
  If this occurs many thousands of times against the same file
  this may lead to CICS becoming unresponsive.  This is because
  the number of holders of the shared FCT lock has exceeded
  32767.  Subsequent unlock attempts result in a tight loop
  within CICS lock manager. In the reported case this was during
  an activity keypoint under a CSKP task.
  A subsequent emergency restart reconstructs these UOWs and the
  same situation can occur then when more than 32767 UOWs have
  shared the FCT lock once more.
  
  Additional keywords: msgdfhfc0578 msgdfhfc0579 fc0578 fc0579
  

Problem conclusion

• DFHFCFS has been modified to issue a new informational message,
  DFHFC0578, if a recoverable VSAM ESDS or BDAM data set is
  opened when no XFCLDEL global user exit program is enabled.
  
  DFHFCMT has been modified to issue a new informational message,
  DFHFC0579, when the last XFCLDEL global user exit program is
  disabled.
  
  The CICS Transaction Server Version 5 Release 1 CICS Messages
  and Codes Vol 1 manual (GC34-2861-00) will be updated as
  follows.  In Chapter 4. DFH messages - DFH01 to DFHM,
  immediately after the description of DFHFC0577, the
  descriptions of messages DFHFC0578 and DFHFC0579 will be added:
  
  DFHFC0578 applid File Control has opened file filename which is
  a recoverable filetype, however no XFCLDEL global user exit
  program is enabled.
  
  Explanation: If CICS is required to back out a unit of work
  that performed a write operation to a VSAM ESDS, or a BDAM data
  set, a backout failure will occur.
  
  System action: None. The message is informational.
  
  User response: To prevent a backout failure in the case
  described above, enable and start a suitable XFCLDEL exit
  program.  For further information, refer to Exit XFCLDEL, file
  control logical delete exit.
  
  Module: DFHFCFS
  
  Message inserts:
  1. applid
  2. filename
  3. filetype
  
  Destination: Console
  
  DFHFC0579 applid The last XFCLDEL global user exit program has
  been disabled.
  
  Explanation: As the result of a DISABLE PROGRAM command, there
  are no XFCLDEL global user exit programs enabled.  If CICS is
  required to back out a unit of work that performed a write
  operation to a VSAM ESDS, or a BDAM data set, a backout failure
  will occur.
  
  System action: None. The message is informational.
  
  User response: To prevent a backout failure in the case
  described above, enable and start a suitable XFCLDEL exit
  program.  For further information, refer to Exit XFCLDEL, file
  control logical delete exit.
  
  Module: DFHFCMT
  
  Message inserts:
  1. applid
  
  Destination: Console
  
  The CICS Transaction Server Version 5 Release 2 CICS Messages
  and Codes Vol 1 manual (GC34-7283-00) will also be updated.
  Immediately after the description of DFHFC0577 in Chapter 4.
  DFH messages - DFH01 to DFHM, descriptions of messages
  DFHFC0578 and DFHFC0579 will be added, as listed above.
  

Temporary fix

• FIX AVAILABLE BY PTF ONLY
  

Comments

• ×**** PE15/08/13 FIX IN ERROR. SEE APAR PI45284  FOR DESCRIPTION
  

APAR Information

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

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

  UI24536 UI24537

Modules/Macros

• DFHFCFS  DFHFCMT  DFHMEFBC DFHMEFBE DFHMEFBK DFHSIC1  DFHUEM
  DFHUEXIT
  

Fix information

• Fixed component name

  CICS TS Z/OS V5

• Fixed component ID

  5655Y0400

Applicable component levels

• R800 PSY UI24536

     UP15/01/30 P F501

• R900 PSY UI24537

     UP15/01/30 P F501

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.