Establishing dependent region connections

MPP and IFP regions

Identify processing for an MPP or an IFP dependent region is similar to identify processing for the control region in that the dependent region automatically activates its Identify exit routine to establish a connection during dependent region initialization, unless the external subsystem defers the identify.

If the control region connection has not been established when the dependent region would automatically identify, IMS attempts to identify the control region. If successful, the dependent region identify is performed. Thus, if the control region identify is deferred but dependent regions are allowed to connect automatically, the control region Identify exit routine might be activated (automatically) when a dependent region is started.

When the identify for a dependent region is deferred, the connection to the external subsystem is established when the first application program call to the external subsystem is issued in the region. In this case, connection processing is the same as for a BMP dependent region.

BMP regions

The connection from a BMP dependent region is not established until the first application call to the external subsystem is processed by the region. The connection is automatically established.

Return code 4 from the Initialization exit routine (deferred identify) for a BMP region has no effect.