PK01098: SLOW GROWTH OF SUBPOOL 231 KEY 6 STORAGE FROM TCP/IP

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• TCP/IP has been configured with DBCSTRANSFORM enabled on one of
  the Telnet (TN3270) ports.  Monitoring of ECSA storage shows a
  slow growth in the usage of subpool 231 key 6 storage.
  Examination of these areas show repeated occurrences of the
  following pattern:
  
    +00 xxxxxxxx xxxxxxxx xxxxx018 06E7025E |bZT.u.....{..X.;|
    +10 E2D2D4C2 00000000 00000000 00000000 |SKMB............|
    +20 00000000 00000000 xxxxxx40 00000000 |..........W ....|
    +30 xxxxxx70 xxxxxxC7 00000000 00000000 |..W...WG........|
    +40 E2D2C4C2 xxxxxx10 00000000 00000000 |SKDB..W.........|
    +50 00000000 00000000 00000000 xxxxxx70 |..............W.|
    +60 00000059 00000000 00000001 00000000 |................|
    +70 1B5B3232 3B31481B 5B306D45 5A593432 |.$......$._.!...|
    +80 34334920 49424D20 5443502F 49502054 |......(...&..&..|
    +90 454C4E45 54205345 52564552 20444243 |.<+.............|
    +A0 53205345 52564943 4520454E 44204154 |...........+....|
    +B0 203x3x3A 3x3x3A3x 3x204F4E 203x3x2F |..........|+....|
    +C0 3x3x2F3x 3x0D0A                     |.......         |
  
  Interpreting the area from +7B to +B0 in ASCII will show the
  following string:
  
   EZY4243I IBM TCP/IP TELNET SERVER DBCS SERVICE END AT...
  
  There will be one of these for each Telnet session that used
  DBCS Transform services that has ended since the TCP/IP
  address space was started.
  
  The potential exists for this storage to grow to the point that
  CSA (or CSM) allocations will fail (S4C5 and S878-08 ABENDs
  from various processes).
  

Local fix

• - Disable DBCSTRANSFORM.
  
  - Recycle the TCPIP stack periodically.
  
  
  CIT: TNL TNST
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of Communications Server           *
  *                 z/OS Version 1 Release 4, Version            *
  *                 1 Release 5 and Version 1 Release 6          *
  *                 IP Telnet facilities using DBCSTRANSFORM.    *
  ****************************************************************
  * PROBLEM DESCRIPTION: ECSA storage growth in subpool 231      *
  *                      key 6.                                  *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The problem may be summarized as follows:
  
  1) DBCSTRANSFORM was specified in the TELNETPARMS section
     of the TCP/IP profile.
  
  2) A VT100 connection was established with the Telnet server.
     DBCSTRANSFORM was utilized for this connection.
  
  3) The connection was then terminated.  Module EZBTTRCV called
     module EZBTTCLS to perform the connection close processing.
     A CMRB was queued to the DBCSTRANSFORM task:
  
     TRMST->TRBYE->TRSTP->TRFTO->TTSND
  
  4) An SKMB was allocated by module EZBTRSTP in subpool 231
     key 6 storage (ECSA).  The SKMB was initialized to contain
     the message:
  
     EZY4243I IBM TCP/IP TELNET SERVER DBCS SERVICE END AT time
              ON date
  
     Module EZBTTSND was eventually called to send the SKMB to
     to the client.  However, since the associated CVB indicated
     that a close was in progress, EZBTTSND did not attempt the
     send.  Control was returned to EZBTRBYE but the SKMB was
     not freed.
  
  5) One SKMB was stranded every time a DBCSTRANSFORM connection
     was ended.
  +-------------------------------------------------------------+
  + 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

• To resolve this problem, the following changes have been
  made:
  
  1) Module EZBTRBYE has been changed to not send the EZY4243I
     message to the client if the CVB (connection control block)
     indicates that a close is in progress.
  
  2) Module EZBTTCCU has been included for maintenance purposes
     only.
  
  * Cross Reference between External and Internal Names
  

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:

  UK01082 UK01084 122PC5Ÿ UK01083 114PC3Ÿ 120AC5Ÿ PK05314

Modules/Macros

• EZBTRBYE EZBTTCCU
  

Fix information

• Fixed component name

  TCP/IP V3 MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R140 PSY UK01082

     UP05/04/21 P F504 Ž

• R150 PSY UK01083

     UP05/04/21 P F504 Ž

• R160 PSY UK01084

     UP05/04/21 P F504 Ž

Fix is available

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