OA18512: ABEND0C4 IN MODULE ISTRACPS CREATING A RESUME (RESM) TRACE ENTRY FOR LLIX PAB (IUTLLCIX) DUE TO FREED ELEMENT ON RPHWEA

APAR status

• Closed as fixed if next.

Error description

• ABEND0C4 in module ISTRACPS creating a RESUME (RESM) trace
  entry for LLIX PAB (IUTLLCIX) due to freed element on RPHWEA
  (RPH Work Element Address).
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All using Enterprise Extender.               *
  ****************************************************************
  * PROBLEM DESCRIPTION: ABEND in ISTRACPS trying to reference   *
  *                      a work element pointed to by RPHWEA     *
  *                      for a RESM trace entry.                 *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The problem may be summarized as follows:
  
  1. A chain of IUTIL PLISTs is sent as MSG_UDATA by TCP/IP
  on a Fast UDP (PTP Samehost) connection.  This is interpreted
  by IUTLLCIX, which escapes to ISTTSC89.
  2. ISTTSC89 passes the data via RPHWEA to the Inbound Data
  Manager (IUTLLCMB).
  3. IUTLLCMB delivers the data to the partner by issuing
  MSG_UDATA_IND.  However, RPHWEA is not reset in the process.
  4. When ISTAUCII interprets the MSG_UDATA_IND, one of the
  PLISTs in the chain prompts an IPTADDRS ADD invocation.
  5. ISTAUCAM gets control as a result and tries to obtain a
  lock that is currently held by another process.  This causes
  a TPWAIT.
  6. Upon TPPOST, PSS resumes the thread and invokes INTRACE
  to cut the trace record.
  7. ISTRACPS, in cutting the RESM entry, tries to reference
  the work element pointed to by RPHWEA.  However, that
  work element is the first PLIST in the chain and had been
  processed independently and freed.  ABEND0C4 results.
  

Problem conclusion

Temporary fix

Comments

• The following change(s) will be included in
  z/OS Communications Server V1R10:
  
  IUTLLCMB will reset RPHWEA once it has secured addressibility
  to the PLIST chain from working storage.  This will prevent
  RPHWEA from propagating residual information and allow the
  RESM entry to be cut without using RPHWEA at all.
  
  ISTAUCLA will be included for maintenance purposes only.
  

APAR Information

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

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

Fix information

Applicable component levels

• R140 PSN

     UP

• R150 PSN

     UP

• R160 PSN

     UP

• R170 PSN

     UP

• R180 PSN

     UP