PK68520: ABEND S0C4 IN WEB SERVER WITH NO IDENTIFIED MODULE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• The z/OS Web Server is configured to use FRCA caching.  If a
  failure occurs during FRCA processing of a sockets call
  (typically, a storage allocation failure), the return from the
  TCP layer to the PFS layer may use a conventional return instead
  of a PR instruction.  This will cause a branch to an address
  that exists in the OMVS address space, but with the PASID still
  set to the TCPIP address space.  This normally will result in a
  PIC 10 interrupt on the instruction fetch.
  
  The resultant dump title will show:
  
    Job(webserve) ........(....... ......)+?????? S0C4/00000010
  

Local fix

• Ensure that sufficient resources are configured, especially CSM
  limits, ECSA size, and ECSALIMIT and POOLLIMIT on the
  GLOBALCONFIG statement.
  
  See Technote 1216034 as well.
    http://www.ibm.com/support/docview.wss?rs=852&uid=swg21216034
  
  
  Other Symptoms:
  
    The SYSTCPIP CTRACE will show an AFP type exception record for
    the failing DUCB prior to the ABEND.
  
    S0C1 ABENDs are also possible.
  
    Some scenarios may pick up a residual value as the branch
    address, causing unpredictable results.
  
  
  Keywords:
  
  ABEND00C4 ABEND00C1
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of the IBM Communications Server   *
  *                 for z/OS Version 1 Release 10 IP:  FRCA      *
  ****************************************************************
  * PROBLEM DESCRIPTION: Abend0C4 in WebServer with FRCA enabled *
  *                      and a persist time configured.  The     *
  *                      abend occurs fetching the instruction   *
  *                      following a branch.  The instruction    *
  *                      address resides in the OMVS address     *
  *                      space and PASID is TCP/IP.              *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Abend0C4 occurs with the WebServer enabled for FRCA with a
  persist time configured.  A client request arrives that can
  not be serviced from the cache.  The connection is queued for
  normal socket processing.  The WebServer accepts the connection
  and processes the pending request.  The WebServer then issues
  a read type operation waiting for the next request to arrive
  on the persistent connection.
  If an error condition occurs during the final read operation
  the TCP socket read module returns using a branch instruction
  instead of a program return.  This results in a new PSW
  address that is not addressable in the primary address space.
  The error that caused this problem to surface was a CSM FIXed
  storage constraint condition.
  +-------------------------------------------------------------+
  + Please check our Communications Server for OS/390 homepages +
  + for common networking tips and fixes.  The URL for these    +
  + homepages can be found in Informational APAR II11334.       +
  +-------------------------------------------------------------+
  

Problem conclusion

• The TCP read module, EZBTCFRD, has been amended to issue a
  program return when an error is detected in the FRCA_Resp
  subroutine.
  
  * Cross Reference between External and Internal Names
  

Temporary fix

Comments

APAR Information

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

  PK65021

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

  UK38177

Modules/Macros

• EZBTCFRD
  

Fix information

• Fixed component name

  TCP/IP V3 MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R1A0 PSY UK38177

     UP08/08/05 P F808

Fix is available

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