APPC DISPLAY Call May Return AP_COMM_SUBSYSTEM_ABENDED.

ID: Q180705

The information in this article applies to:

Microsoft SNA Server, versions 3.0, 3.0 SP1, 3.0 SP2, 4.0

SYMPTOMS

If a Win32 APPC application calls the SNA Server DISPLAY function to retrieve a list of all configured remote APPC LU's (in other words, sets the plu_def_info option), the following symptoms may occur:

the DISPLAY call may return with the following error:

primary_rc = 0xF003 (AP_COMM_SUBSYSTEM_ABENDED)

The following event may appear in the Windows NT application event log:

Event ID: 706
Source: SNA Server
Description:
Connection to client <client>has been aborted due to too many (100)
pending writes.

This problem has been observed when configuring IBM Personal Communications for the AS/400 (version 4.1) while using the SNA Server Windows NT or Windows 95 client software. This problem occurs when the SNA Server is configured with a large number of local APPC LU/remote APPC LU/mode partnerships. In the customer's failure scenario, there were over 2300 local APPC LU's configured, each partnered with up to 4 remote APPC LU's.

CAUSE

The SNA Server was incorrectly reporting information on all the local APPC LU's defined, even though the application was only requesting remote APPC LUs (via the plu_def_info option). When attempting to send this large response to the client's DISPLAY request, the SNA Server exceeded 100 consecutive pending write requests to the client, causing the default "MaxPendingWrites" counter to be exceeded. For more information about Event 706 and MaxPendingWrites, see the following article in the Microsoft Knowledge Base:

Q142037 SNA Server Fails to Release Memory in SNA TCP/IP Interface DLL

STATUS

Microsoft has confirmed this to be a problem in SNA Server version 3.0, 3.0 Service Pack 1 (SP1), 3.0 SP2 and 4.0.

This problem was corrected in the latest SNA Server versions 3.0 and 4.0 U.S. Service Packs. For information on obtaining these Service Packs, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K

Additional query words:

Keywords : kbbug4.00 prodsna snaappc kbbug3.00 snaprog kbbug3.00.sp2 kbfix3.00.sp3 kbbug3.00.sp1 snaserverservice
Version : WINDOWS:3.0,3.0 SP1,3.0 SP2,4.0
Platform : WINDOWS
Issue type : kbbug