gtpd1m31Database Reference

Disconnecting from a Coupling Facility Structure

A connected TPF system can disconnect from a CF structure when you no longer require access to that structure. Once disconnected, the TPF system cannot access the CF structure through any connection services.

TPF systems disconnect from a CF structure either for normal processing or because of a failure. The connect token is invalidated for the disconnecting TPF system.

Disconnection Parameters for the Coupling Facility Structure

The CFDISC macro allows you to disconnect from a CF structure when you no longer require access to it. You can disconnect from only one CF structure at a time. If you want to disconnect from multiple CF structures, issue the CFDISC macro once for each CF structure.

The CFDISC macro requires you to provide the connect token on the CONTOKEN parameter that was returned by the connection services when the initial connection to the CF structure was made with the CFCONC macro.

See TPF System Macros for more information about the CFDISC macro.

Persistence Considerations

Structure persistence is defined at connect time using the STRDISP parameter of the CFCONC macro. Coding STRDISP=KEEP and STRDISP=DELETE indicates whether a CF structure will become undefined after all TPF systems have disconnected from it. See Specifying Structure Attributes for Coupling Facility Structures for more information about the STRDISP parameter. See TPF System Macros for more information about the CFCONC macro.

The TPF system releases the connection to the CF structure when a normal disconnect occurs. You can also disconnect from the CF structure in an error recovery condition.

Handling Resources for a Disconnection

After all active TPF systems have disconnected from the CF structure, connection services either deletes or retains the CF structure depending on the structure disposition you specified for the STRDISP parameter of the CFCONC macro. See Defining Structure Attributes for Coupling Facility Structures for more information.

Whether the disconnect is normal or the result of an error, the TPF system cleans up resources for a CF structure. For example, the list monitoring interest, if registered, is released.

Successfully Completing a Disconnection

The connect token for the TPF system is invalidated before returning control to the TPF system that issued the CFDISC macro. This ensures that the TPF system cannot issue additional connection services mainline requests. If the TPF system does use the invalidated connect token to issue a request for connection services, the request fails.