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LUA App May Hang If VTAM Recycled While RUI_WRITE Outstanding

This article was previously published under Q311584
This article has been archived. It is offered "as is" and will no longer be updated.
A logical unit application (LUA) application may stop responding ("hang") if it has an outstanding RUI_WRITE when Virtual Telecommunications Access Method (VTAM) is recycled on the IBM mainframe.

This can occur when the RUI_WRITE was issued to send an INITSELF Request Unit (RU) to the host system.
If VTAM is unavailable when an LUA application issues an RUI_WRITE(INITSELF) to an IBM mainframe, the INITSELF may not be responded to. Once VTAM is available, it may issue an ACTLU(ERP) to recover the session over which the LUA application was communicating. When this occurs, the Request Unit Interface (RUI) library (Winrui32.dll) does not return an error on the outstanding RUI_WRITE() verb when the host issues the ACTLU(ERP) to recover the session. The result is that the outstanding RUI_WRITE() verb never finishes, which may cause the LUA application to stop responding.

SNA Server 4.0

No fix is available for this problem in SNA Server 4.0 at this time.

Host Integration Server 2000

To resolve this problem, obtain the latest service pack for Host Integration Server 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
328152 How to Obtain the Latest Host Integration Server 2000 Service Pack
The English version of this fix should have the following file attributes or later:

File nameDateTime

NOTE: Because of file dependencies, the most recent fix that contains the preceding files may also contain additional files.

NOTE: If this product was already installed on your computer when you purchased it from the Original Equipment Manufacturer (OEM) and you need this fix, please call the Pay Per Incident number listed on the above Web site. If you contact Microsoft to obtain this fix, and if it is determined that you only require the fix you requested, no fee will be charged. However, if you request additional technical support, and if your no-charge technical support period has expired, or if you are not eligible for standard no-charge technical support, you may be charged a non-refundable fee.

SNA Server 4.0

Microsoft has confirmed that this is a problem in Microsoft SNA Server version 4.0,.

Host Integration Server 2000

Microsoft has confirmed that this is a problem in Microsoft Host Integration Server 2000. This problem was first corrected in Host Integration Server 2000 Service Pack 1.
The following is an example of a scenario that can result in the problem described in this article:

LUA ApplicationSNA/HIS 2000 ServerHost
NOTIFY(SLU Enabled) ->
<- FMIST(LU Reactivated)

The IBM mainframe doesn't respond to the INITSELF because VTAM is not available. Once VTAM is available, it sends an ACTLU(ERP) to recover the session. The SNA Server service (Snaservr.exe) responds to the ACTLU(ERP) with the NOTIFY and it sends a Function Management Interface (FMI) Session Status (LU Reactivated) message to the RUI library. The RUI library fails to return an error on the outstanding RUI_WRITE to indicate that the RUI_WRITE will not be responded to.

For additional information on SNA Server and Host Integration Server 2000 support for ACTPU(ERP) and ACTLU(ERP) RUs, click the article number below to view the article in the Microsoft Knowledge Base:
138469 SNA Server Support for ACTPU (ERP) and ACTLU (ERP)
HIS 2000

Article ID: 311584 - Last Review: 10/24/2013 08:19:43 - Revision: 4.0

Microsoft SNA Server 4.0, Microsoft Host Integration Server 2000 Standard Edition

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