SNA Server Incorrectly Handles Cancelled Allocate Requests (195996)

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: <WWLINK TYPE="ARTICLE" VALUE="Q193659">Q193659</WWLINK>

   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, click the following article number to view the article in the Microsoft Knowledge Base:

184307 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