OW04566: 2 INOPS-APPN HOST TO HOST PU ACT FAILURE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• A link failure occured during activation of an APPN Host to
  Host Channel connection. This caused a station INOP (message
  IST259I) on the underlying MPC subchannel before the link
  was fully active. Immediately after the station INOP, another
  station INOP was received for the same link failure even though
  nothing further had failed. Also, if XID exchange fails during
  APPN Host to Host Channel connection activation and message
  IST467I is received for a CONTACTED Type 0B, subsequent messages
  IST468I, 469I, 470I, and 471I may contain erroneous XID data.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All using APPN Host to Host Channel          *
  *                 connections.                                 *
  ****************************************************************
  * PROBLEM DESCRIPTION: A link failure occured during           *
  *                      activation of an APPN Host to Host      *
  *                      Channel connection. This caused a       *
  *                      station INOP (message IST259I) on the   *
  *                      underlying MPC link before the link     *
  *                      was fully active. Immediately after     *
  *                      the station INOP, another station INOP  *
  *                      was received for the same link failure  *
  *                      even though nothing further had         *
  *                      failed.                                 *
  *                                                              *
  *                      Also during activation of an APPN       *
  *                      Host to Host Channel connection, if     *
  *                      XID exchange fails and IST467I is       *
  *                      issued for a CONTACTED type 0B,         *
  *                      subsequent messages 468I, 469I,         *
  *                      470I and 471I may contain erroneous     *
  *                      XID data. It is possible in certain     *
  *                      scenarios that an addressing exception  *
  *                      (0C4) ABEND may occur.                  *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  If a link failure occurs during the activation of an MPC
  subchannel that is part of a TRLE for an APPN Host to Host
  channel (AHHC) PU, the INOP will be received in MPC for that
  subchannel. The INOP will cause activation failure (negative
  response to OPENPATH) and the request for inactivation of the
  APPN Host to Host channel PU. ISTTSC9L will currently send an
  INOP to PUNS because of the negative response to OPENPATH.
  Then, when the INOP is received from MPC, ISTTSC9L will send
  another INOP to PUNS for the same error. Though not fatal, it
  does cause redundant messages IST259I, IST493I, IST619I and
  IST129I, making it appear there were 2 link errors rather than
  one.
  
  If an XID exchange error occurs during the activation of an MPC
  subchannel that is part of a TRLE for an APPN Host to Host
  channel (AHHC) PU, and CONTACT has already been received from
  PUNS by the AHHC component, AHHC will correctly attempt to
  send a CONTACTED(0B) to PUNS to indicate the failure. However,
  the module that sends the CONTACTED(0B), ISTTSC9C, currently
  cleans up parts of the NCB before building the CONTACTED.
  One of those parts of the NCB that is cleaned up is the
  releasing of the TSCB that contains the XID that was in error.
  Hence, the part of the code that builds the XID for the
  CONTACTED points to low core, and the CONTACTED is built
  in error. In a real MVS system, this could cause an ABEND or
  could cause erroneous XID data in a message, depending on
  what storage is pointed to.
  

Problem conclusion

• The fix for the double INOP problem is for module ISTTSC9L
  to set a bit in the ISTAHNCB when a station INOP is sent to
  PUNS. If a subsequent INOP is received from MPC, it is merely
  discarded.
  
  The fix for the bad XID data in the CONTACTED(0B) is for
  module ISTTSC9C to invoke the subroutine that builds the
  CONTACTED(0B) before invoking subroutine CLEANNCB to clean
  up the NCB.
  

Temporary fix

Comments

APAR Information

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

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

  UW06336

Modules/Macros

• ISTAHNCB ISTTSC9C ISTTSC9L
  

Fix information

• Fixed component name

  VTAM V4 MVS/ESA

• Fixed component ID

  569511701

Applicable component levels

• R201 PSY UW06336

     UP94/05/10 P F405

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.