The SESTIMEOUT registry parameter sets the number of 5-second timer ticks that are allowed before the Microsoft SNA Server service deactivates Advanced Program-to-Program Communication (APPC) Logical Unit (LU) 6.2 contention winner sessions that are no longer used by active APPC conversations. If the registry parameter is not set, 4 timer ticks of 5 seconds each are allowed, for a total of 20 seconds.

Note The SESTIMEOUT registry parameter only applies to LU 6.2 contention winner sessions that Microsoft Host Integration Server initiates.

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

The SESTIMEOUT registry parameter must be added if you want to change the default value of 4. To change this value, follow these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate, and then click the following key in the registry:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SnaServr\Parameters
3. On the Edit menu, point to New, and then click String Value.
4. Type SESTIMEOUT, and then press ENTER.
5. On the Edit menu, click Modify.
6. Type the number of 5-second timer ticks that you want, and then click OK.
7. Quit Registry Editor.

Note If SESTIMEOUT is set to 0, the SNA Server service will not time out a contention winner session that is not being used by an active APPC conversation.

The SNA Server service uses the SESTIMEOUT registry parameter to control how long an LU 6.2 session remains bound after an APPC conversation ends. This parameter applies to LU 6.2 sessions that are not autoactivated. If another APPC session is requested during the SESTIMEOUT period, the existing APPC session is used without having to bind another session. Overall performance is improved when an existing session is used because a new BIND exchange is not required.

If you set the SESSTIMEOUT parameter to 0, the following situations may cause the SNA Server service to unbind a contention winner session:

• The APPC session ends abnormally because the client issues a Cancel request. A CLOSE ERR error message is then sent to the SNA Server service or to the Host Integration Server service.
• The transaction program (TP) issues a TP_ENDED (HARD) verb.

In these situations, the SNA Server service will unbind the session with an UNBIND cleanup to make sure that the condition is cleared.

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