PK22689: ABENDSA03 OCCURS FOR THE IPT TCB AND DAUGHTER S8 TCBS RECEIVE ABENDS422

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• AbendSA03 occurs under the IPT TCB (Initial PTHREAD task).
  Kernel error data shows abendS422 occurring for the daughter
  S8 TCBs leading up to the abendSA03. System trace shows that
  the SVC3 EXIT has been issued by IEAVCVT +x'92'. At the time of
  the dump, CICS is not shutting down. The IPT TCB runs more or
  less invisibly so there is no trace or other diagnostic
  information produced in the run up to the abendSA03.
  .
  The problem appears to be a PTHREAD_CREATE call that failed.
  The dump shows that the MAXSSLTCBS SIT parameter was set to 252.
  However, the USS MAXTHREADS parameter is the default shipped
  value of 200, and there are 200 S8 TCBs currently in the system.
  DFHLEPT does not handle a PTHREAD_CREATE failure, and no
  diagnostic or error information is provided at time of abendA03.
  

Local fix

• Ensure that the SIT parameter MAXSSLTCBS is less than the USS
  MAXTHREADS parameter.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All.                                         *
  ****************************************************************
  * PROBLEM DESCRIPTION: AbendSA03 occurs under the IPT TCB      *
  *                      when pthread_create fails due to        *
  *                      reaching MAXTHREADS limit.              *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  SIT parameter MAXSSLTCBS had been set to 252 but the UNIX System
  Services MAXTHREADS parameter was set to 200. Each CICS S8 TCB
  (used for SSL processing) uses a USS thread. CICS had already
  created 200 S8 TCBs. When it attempted to create another S8,
  the USS pthread_create call failed.
  The initial pthread TCB which issued the pthread_create
  call reacted by terminating prematurely. This lead to an SA03
  abend. After the initial pthread TCB terminates, all the S8
  TCBs (which are daughters of the IPT TCB) will suffer errors
  and all SSL functions within CICS are lost requiring the region
  to be recycled.
  There are no guidelines in the CICS documentation for setting
  either the USS MAXTHREADS or MAXTHREADTASKS parameters when
  running CICS with SSL.
  
  ADDITIONAL KEYWORDS :- A03 ABENDA03 DFHAP0001 MSGDFHAP0001
                         AP0001 ASRA ABENDASRA AKEA ABENDAKEA
                         DFHSO0002 MSGDFHSO0001 SO0001 0814
                         DFHXS0001 MSGDFHXS0001 0A8A DFHSM0002
                         MSGDFHSM0002 SM0002 0320
  

Problem conclusion

• The main dispatch loop for the initial pthread TCB (routine
  dispatch_pthread in module DFHLEPTC) has been changed to return
  an error to its caller rather than terminating when it
  encounters a pthread_create error.
  When this happens, the attempt to add the S8 TCB will terminate
  abnormally and the SSL operation for the currently executing
  task will fail. However, the SSL environment will be preserved
  and any SSL operations being performed by existing S8 TCBs will
  be unaffected by this failure.
  .
  The CICS TS 3.1 System Definition Guide ( SC34642803 ) will be
  updated. In chapter 17 - Specifying CICS system initialization
  parameters, a new paragraph will be added to the end of the
  section entitled 'TCB considerations with UNIX System Services'
  as follows :-
  
   In USS, the MAXTHREADS and MAXTHREADTASKS parameters can be
   used to restrict the number of pthreads which a USS process
   can own.
   Each SSL TCB requires a pthread and an MVS task. You should
   therefore ensure that both the MAXTHREADS and MAXTHREADTASKS
   limits exceed the MAXSSLTCBS SIT parameter. Failure to do so
   can lead to errors during CICS execution.
   If you fail to set a large enough value for MAXTHREADS or
   MAXTHREADTASKS and CICS reaches one of these limits while
   attempting to attach an SSL TCB, this will lead to message
   DFHDS0002 severe error code X'0137' from DFHDSIT.
  
  In the same chapter, under the section entitled 'The system
  initialization parameter descriptions', the MAXSSLTCBS
  description will be changed to read as follows :-
  
   Specifies the maximum number of S8 TCBs that can run in the SSL
   pool. The default is 8, but you can specify up to 1024 TCBs.
  
   This should not exceed the value of the MAXTHREADS or
   MAXTHREADTASKS parameters of SYS1.PARMLIB member BPXPRMxx.
  
  The CICS TS 3.1 Installation Guide ( GC34642603 ) will be
  updated. In Chapter 10 (Defining CICS as an MVS subsystem),
  a new bullet will be added to the list of bullets in the
  section entitled 'The SYS1.PARMLIB(BPXPRMxx) parameters' :-
  
   . SSL TCBs specified by the MAXSSLTCBS SIT parameters.
  
  At the end of this section, the following new sentence will be
  added :-
  
   If CICS is configured to use SSL, you may need to increase the
   MAXTHREADS and MAXTHREADTASKS values. These should exceed the
   MAXSSLTCBS SIT parameter.
  

Temporary fix

•             *********
              * HIPER *
              *********
  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:

  UK16637 UK16638

Modules/Macros

•    DESLEPT  DESSOSE  DFHLEPT  DFHLEPT@ DFHLEPTC
  DFHLEPTI DFHSOSE
  

Fix information

• Fixed component name

  CICSTS 3.1 Z/OS

• Fixed component ID

  5655M1500

Applicable component levels

• R400 PSY UK16637

     UP06/07/29 P F607

• R403 PSY UK16638

     UP06/07/29 P F607

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.