VM66308: ISFC CORRECTIVE SERVICE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• z/VM systems in an ISFC collection may hang during shutdown or
  (on rare occasions) update obsolete message storage, leading
  to unpredictable behavior (potentially including an abend).
  (1) HCPCMSRD and HCPCMRCM may launch tasks that depend on
      user VMDBK being dispatched to obtain and release locks.
      During System Shutdown this can result in a ISFC Global Lock
      hang during system SHUTDOWN (preventing or delaying re-IPL).
  (2) In a rare timing sequence, SSI messages sent via HCPKCCTX
      and HCPKCWTX may be sent successfully and released before
      HCPKCWTX can return to HCPKCCTX (where HCPKCCTX clears
      error status on an MBHBK which may no longer belong to
      that task). If that storage has already been reassigned
      the alteration could cause unpredictable behavior.
  

Local fix

• Apply PTF
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: z/VM systems connected via ISFC links.       *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  ****************************************************************
  * RECOMMENDATION: APPLY PTF                                    *
  ****************************************************************
  This update addresses the following problems:
  (1) SSI client traffic sometimes hangs with no explanation.
  (2) CP SHUTDOWN hangs (usually after system services are
      already showing signs of a hang).
  

Problem conclusion

• This update provides:
  (1) HCPKCCTX (a transmit function for SSI traffic) is modified
      to avoid altering the outbound message (represented by an
      MBHBK) after a successful return from HCPKCWTX (a low-level
      transmit function). Some diagnostic code is added as well.
  (2) HCPWRP is modified to invoke a new function (HCPBINSP) to
      alert the ISFC subsystem that Shutdown is Pending. This
      allows ISFC to set a flag to prevent certain tasks from
      being started (tasks like IUCV functions that depend on
      a VM user being dispatched so ISFC can complete its
      shutdown operations). Otherwise SYSUHOLD can be set
      while ISFC is waiting for a user to be dispatched.
  

Temporary fix

• FOR RELEASE VM/ESACP/ESAR710 :
  PREREQ: NONE
  CO-REQ: NONE
  IF-REQ: NONE
  

Comments

APAR Information

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

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

  UM35541

Modules/Macros

• HCPACQ   HCPBIN   HCPBUU   HCPCMR   HCPCMS   HCPKCC   HCPKCD
  HCPKCW   HCPWRP
  

Fix information

• Fixed component name

  VM CP

• Fixed component ID

  568411202

Applicable component levels

• R710 PSY UM35541

     UP19/09/30 P 2001  

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.