PI67798: TN3270 delivers old information to the application

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• TN3270 receives data from the client after the application has
  already said it is about to send a new panel.  TN3270 queues the
  data from the client and when the application does send the new
  panel, TN3270 forwards the data, which is now old and no longer
  relevant.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All users of the IBM Communications Server                   *
  * z/OS Version 2 Releases 1 and 2: IP Telnet facilities        *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * Old data is allowed to be sent from the terminal to the      *
  * application                                                  *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply PTF                                                    *
  ****************************************************************
  The problem may be summarized as follows:
  
  1. Host application sends a panel to the client with BB,EB.
  2. An enter key is sent from the client along with data, locking
  the keyboard.
  3. The enter key is forwarded from the Telnet server to the
  application with BB and CDI.
  4. The application receives the data and then sends a null RU to
  the client with EB.  The telnet server unlocks the client's
  keyboard by sending a standalone x'F1C2' write command with
  keyboard restore specified in the WCC.
  5. The application sends a bid RU to the Telnet server.
  6. The Telnet server returns a positive response to the bid.
  The client's keyboard remains unlocked.
  7. The enter key is again pressed from the client (locking the
  keyboard).
  8. The Telnet server receives the enter key and detects that a
  bid response was previously sent so the data cannot be
  delivered.  The data is queued.
  9. The application sends a new panel to client with BB,EB.  The
  client's keyboard is unlocked, but the queued data is also now
  delivered.
  10. The queued data does not match the new panel and could cause
  problems.
  

Problem conclusion

• Telnet is modified to discard the data in these, and similar,
  circumstances rather than queueing it if a new parameter,
  LIMITQ, is specified in the TelnetGlobals section.
  
  
  The z/OS Communications Server: IP Configuration Reference is
  updated as follows:
  
  In the Telnet chapter, the section named "Telnet parameter
  statements in the Telnet profile" will document a new parameter
  statement:
  
  LIMITQ
  
  Use the LIMITQ parameter statement to indicate that Telnet
  should not queue up data for later delivery if data is received
  from an emulator when Telnet does not have direction to send on
  the session.
  
  Telnet is initialized with a value of NOLIMITQ.
  
  The LIMITQ and NOLIMITQ statements can be coded in the
  TELNETGLOBALS statement block only.
  
  Syntax
  
  >>__ ____________
  ________________________________________________________________
  ___________________________________________________><
  |_NOLIMITQ__| |_LIMITQ___|
  
  Parameters
  
  This statement has no parameters.
  

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:

  UI40694 UI40695

Modules/Macros

• EZBTVXR2 EZBTVXS2 EZBCTFME EZBTDPRU EZBTMPRT EZBTVSRP EZBTPHDO
  EZBTMPRP EZBTDPRM EZBTZMSG EZBTMQPR EZBDGPRG EZBTMQCI EZBTMQTD
  

Fix information

• Fixed component name

  TCP/IP V3 MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R210 PSY UI40694

     UP17/05/06 P F705

• R220 PSY UI40695

     UP17/05/06 P F705

Fix is available

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