PK18930: LOCKOUT BETWEEN RESOURCES ENQUEUE KCSTRING AND CCSTWAIT VSMSTRNG

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• 5697E9300
  Many tasks are in waits for CCSTWAIT VSMSTRING and enqueues
  for ENQUEUE KCSTRING. EXEC CICS CREATE commands are being issued
  by tasks which cause ENQUEUE KCSTRING for resourse DFHTOR:tt:mm
  . Because of the creates, CICS must also write to the catalog
  causing the need for VSMSTRING as well. It appears no GCTHREADS
  are available as each has a token at x'14'. All tasks associated
  with GCTHREADS are waiting for KCSTRING (DFHTOR:tt:mm) and the
  owner of KCSTRING is waiting for a VSMSTRING. Thus, lockout.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All.                                         *
  ****************************************************************
  * PROBLEM DESCRIPTION: Deadlock occurs for TERMINAL resources  *
  *                      between ENQUEUE KCSTRING and CCSTWATT   *
  *                      VSMSTRING.                              *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  A large number of EXEC CICS CREATE TERMINAL commands, for
  pooled terminals, are executed each within a new task. The
  first task issues a DFHCCCC call for START_WRITE which obtains
  a VSAM catalog string. It then calls DFHTOR which acquires an
  enqueue on 'DFHTOR:tt:mm'. This ENQUEUE will be held
  until the EXEC CICS CREATE TERMINAL COMPLETE command is
  issued. More tasks which issue CREATE TERMINAL commands
  have now started, obtained a VSAM catalog string, and then
  waited for the ENQUEUE on DFHTOR:tt:mm to be released. The first
  task now wants to issue the CREATE TERMINAL COMPLETE command.
  This command tries to obtain a VSAM catalog string, however
  there is a maximum limit on the number of VSAM catalog strings
  and this has been used up by all the other tasks.
  So the first task waits for a string while holding the ENQUEUE
  that all the tasks which are using up the strings are waiting
  for, resulting in a deadlock.
  Additional keywords: VSMSTRING KCSTRING HANG HUNG
  

Problem conclusion

• DFHAMPIL has been altered so that the DFHCCCC call for
  START_WRITE does not occur if an EXEC CICS CREATE TERMINAL
  for a pooled terminal is issued. This ensures that a VSAM
  catalog string is only allocated when it is required.
  

Temporary fix

• FIX AVAILABLE BY PTF ONLY
  

Comments

APAR Information

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

  PK14963

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

  UK12017

Modules/Macros

•    DFHAMPIL
  

Fix information

• Fixed component name

  CICSTS 3.1 Z/OS

• Fixed component ID

  5655M1500

Applicable component levels

• R400 PSY UK12017

     UP06/02/28 P F602

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.