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PM72871: UNPREDICTABLE ABENDS IN IDLE TN3270 SERVER AFTER MAINTENANCE

A fix is available

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APAR status

  • Closed as program error.

Error description

  • A TN3270 server is started, but sits idle (no client connections
    that ever establish an SNA session) after that.  If any
    maintenance (PTFs) is applied that affects the EZBTTMST load
    module in the active SEZALOAD library (and an LLA REFRESH is
    performed), the potential exists for unpredictable ABENDs to
    occur when a client finally does start a session that connects
    to an SNA application.
    
    
    Other symptoms:
    
       Analysis of the resultant dump will show the ABEND occurring
       immediately after a new task running EZBTTTSK is first
       dispatched.  The entry point address in the CDE for EZBTTTSK
       does not reference the BRANCH RELATIVE instruction that
       immediately precedes the routine's eye-catcher.
    

Local fix

  • Ensure that at least one session is started that begins
    communicating with an SNA application (does an OPEN ACB) before
    any maintenance is applied to a live system.
    
    OR
    
    Recycle the TN3270 server after the maintenance is applied.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All users of the IBM Communications Server   *
    *                 for z/OS Version 1 Releases 12 and 13 IP:    *
    *                 Telnet facilities.                           *
    ****************************************************************
    * PROBLEM DESCRIPTION: Various abends are possible due to      *
    *                      partial maintenance applied.            *
    *                                                              *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    The problem is summarized as follows:
    1. The TN3270 server is started.
    2. Sometime later, maintenance that hits the EZBTTMST load
       module is applied.
    3. Sometime later, the first Telnet connection occurs and
       the connection logs onto a VTAM application.
    4. As a result, there may be two copies of the EZBTTMST
       load module in storage and some of the maintenance in
       one of the modules may be a mismatch of maintenance in
       other load modules loaded when Telnet was started.  This
       can lead to ABENDs and other unpredictable results.
    +-------------------------------------------------------------+
    + 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

  • EZBTNINI is updated to load alias EZBTTTSK so that when
    the first connection is made, there is no attempt to load
    a second copy of EZBTTMST.
    
    * Cross Reference between External and Internal Names
    

Temporary fix

Comments

APAR Information

  • APAR number

    PM72871

  • Reported component name

    TCP/IP V3 MVS

  • Reported component ID

    5655HAL00

  • Reported release

    1C0

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-09-13

  • Closed date

    2012-09-19

  • Last modified date

    2012-11-02

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

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

    UK81913 UK81914

Modules/Macros

  • EZBTNINI
    

Fix information

  • Fixed component name

    TCP/IP V3 MVS

  • Fixed component ID

    5655HAL00

Applicable component levels

  • R1C0 PSY UK81913

       UP12/10/25 P F210

  • R1D0 PSY UK81914

       UP12/10/25 P F210

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.

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Document Information

Modified date:
02 November 2012