Using Advanced Program-to-Program Communication › Conversation Allocation › Allocation and Sessions

Allocation and Sessions

To complete an allocation to a remote destination a session is required. If no session to that destination currently exists, then for all requests except &APPC ALLOCATE_IMMEDIATE, an attempt will be made to establish an APPC link to the remote LU. Other than the fact that it is an automatic link activation request, the result is no different from an operator starting a link by command.

For the &APPC ALLOCATE_SESSION and ALLOCATE_NOTIFY requests, the verb will not complete until a session can be assigned for the conversation. This can involve waiting for new sessions to be established, or waiting for active conversations to end and free up a session.

For the &APPC ALLOCATE_DELAYED request, a delayed session assignment is allowed. The verb completes as though a session can be assigned and processing continues. However, if transmission is actually required at some stage, the procedure will be suspended until session assignment can be performed.

The &APPC ALLOCATE_IMMEDIATE request only completes successfully if a session can be guaranteed immediately for transmission.