Q195996: SNA Server Incorrectly Handles Cancelled Allocate Requests

Article: Q195996
Product(s): Microsoft SNA Server
Version(s): 3.0,3.0 SP1,3.0 SP2,3.0 SP3,4.0,4.0 SP1
Operating System(s): 
Keyword(s): 
Last Modified: 24-OCT-2001

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The information in this article applies to:

- Microsoft SNA Server, versions 3.0, 3.0 SP1, 3.0 SP2, 3.0 SP3, 4.0, 4.0 SP1 
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SYMPTOMS
========

The following symptoms can occur when SNA Server incorrectly handles cancelled
allocate requests:

- An Advanced Program-to-Program Communications (APPC) or Common Programming
  Interface for Communications (CPIC) application's call to [MC_]ALLOCATE or
  CMALLC may hang indefinitely. This may occur after a previous allocation
  request has been cancelled, or after the SNA Server connection has been
  restarted.

- If an APPC or CPIC application subsequently cancels an outstanding
  [MC_]ALLOCATE or CMALLC request (by calling the cancel verb, or by calling
  TP_ENDED, or if the client-server LAN session is lost), the SNA Server may
  later fail unexpectedly with an access violation (C0000005) in routine
  s1prfrcb() or s1puc62() as indicated by the Drwtsn32.log entry.

The following Knowledge Base article has additional information when this problem
results in an access violation in the s1prfrcb() routine:

  Article ID: <LINK TYPE="ARTICLE" VALUE="Q193659">Q193659</LINK>

  Title: SNA Server Access Violation in s1prfrcb()

CAUSE
=====

SNA Server was incorrectly handling the cancellation of a pending [MC_]ALLOCATE
or CMALLC request. This caused the SNA Server to prevent unused LU 6.2 sessions
from being used. If many cancelled client allocation requests are received, this
could lead to an SNA Server access violation.


RESOLUTION
==========

SNA Server 3.0
--------------

To resolve this problem, obtain the latest service pack for SNA Server version
3.0. For additional information, please see the following article in the
Microsoft Knowledge Base:

  Q184307 How to Obtain the Latest SNA Server Version 3.0 Service Pack



SNA Server 4.0
--------------

This problem was corrected in the latest SNA Server version 4.0 U.S. Service
Pack. For information on obtaining this Service Pack, query on the following
word in the Microsoft Knowledge Base (without the spaces):

  S E R V P A C K


STATUS
======

Microsoft has confirmed this to be a problem in SNA Server versions 3.0, 3.0
Service Pack 1, 3.0 Service Pack 2, 3.0 Service Pack 3, 4.0, and 4.0 Service
Pack 1. This problem was first corrected in SNA Server 3.0 Service Pack 4.

Additional query words:

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Keywords          :  
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ400 kbSNAServ300SP3 kbSNAServ300SP1 kbSNAServ400SP1 kbSNAServ300SP2
Version           : :3.0,3.0 SP1,3.0 SP2,3.0 SP3,4.0,4.0 SP1
Issue type        : kbbug
Solution Type     : kbfix

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