OA23793: ABEND0C7 IN ISTRACOT WHEN CALLED BY ISTRPCPC TO WRITE NEXT MESSAGE AFTER IST1494I PATH SWITCH STARTED FOR RTP

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• ISTRPCPC causes an ABEND0C7 in ISTRACOT by issuing CPMSG macro
  with a corrupted MSGID parameter.  The field used to set MSGID
  was overlaid when ISTRPCPC attempted to build a fully qualified
  CPNAME for message IST1494I using the fields RPN_ALS_NETID and
  RPN_ALS_CPNAME which were all blanks in the RPNCB.  IST1494I was
  issued with an invalid CPNAME field and then ISTRACOT abended
  when CPMSG was issued with the bad MSGID parameter for the path
  switch reason message.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All using HPR/RTP connections.               *
  ****************************************************************
  * PROBLEM DESCRIPTION: ABEND0C7 in ISTRACOT during processing  *
  *                      of an HPR path switch message.          *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The problem is summarized as follows:
  1) An EE connection, with established CP-CP sessions, is
     inactivated by the receipt of an unexpected XID sent
     from the partner.  This generally indicates the partner
     recycled its end of the connection and this end is unaware
     of the outage until now.
  2) The CP-CP RTP pipes enter path switch.
  3) RCM sends an RST (RTP_Setup) IPS to Session Services for
     processing.  This eventually leads to Configuration
     Services dialing the outbound switched PU for the EE
     connection.
  4) The dial completes and the RST response IPS is sent
     back to RCM.
  5) RCM then builds an RAS (RTP_Allocation) IPS signal and sends
     it to Configuration Services (to dynamically allocate a
     PU for the connection).  The RAS IPS is incorrectly built
     in that the NETID and CPNAME are both blank.
  6) This leads to the new CNRxxxxx RTP PU having a blank NETID
     and CPNAME in the RDTE entry.
  7) Later, when RCM allocates the RPNCB control block to
     represent the CP-CP (CPSVCMG) pipe, the blank NETID and
     CPNAME are propogated to the RPNCB.
  8) At some point later, connectivity to the remote partner is
     interrupted, and the new RPNCB enters path switch.
  9) When building the path switch messages (IST1494I) using
     the BLDNQN macro, an overlay occurs in the MSGID parameters
     which result in an ABEND0C7 in ISTRACOT.
  10) During pipe establishment, an overlay of the
      ISTRPNCB_BaseExt occurs at field RPN_FQ_CPNAME for 256
      bytes.  This overlay occurs when ISTRPCDU sets up this field
      using the BLDNQN macro with the blank NETID and CPNAME.  The
      overlay is confined to the RPNCB_BaseExt.
  
  This APAR is being marked HIPER because control blocks are
  inadvertantly overlayed.  Results due to these overlays are
  unpredictable.
  

Problem conclusion

• ISTRCCAS - Code modifications made to correctly build the RAL
             IPS with the correct NETID and CPNAME.  Also, the
             RAL response IPS is now traced via the APSEND
             macro invocation (CPI VIT entry).
  
  ISTRPCRT - Included for maintenance purposes.
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

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

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

  UA39519 UA39520 UA39521

Modules/Macros

• ISTRCCAS ISTRPCRT
  

Fix information

• Fixed component name

  VTAM V4 MVS/ESA

• Fixed component ID

  569511701

Applicable component levels

• R170 PSY UA39519

     UP08/03/21 P F803 Ž

• R180 PSY UA39520

     UP08/03/21 P F803 Ž

• R190 PSY UA39521

     UP08/03/21 P F803 Ž

Fix is available

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