The APPCDATA SERVERDATA subcommand displays information about allocate queues and APPC/MVS servers. An APPC/MVS server is an address space that has requested that certain inbound allocate requests be directed to it, rather than to a transaction scheduler. When a server receives an allocate request, a conversation takes place between it and the TP that issued the allocate request. Typically, the TP requires that some function be performed on its behalf by the server. The server processes, or serves, the TP's request by performing the requested function. Depending on how it is designed, a server may serve multiple allocate requests concurrently.
An installation can have any number of servers. In addition, an installation can choose to have one or more transaction schedulers active.
APPC/MVS servers select a subset of inbound allocate requests through a process called registering. Servers register for allocate requests that bear a specific combination of TP name and the name of the LU that was targeted by the allocate request. Servers can further limit their selection of requests by specifying certain “filters”: user ID, security profile, and partner LU.
APPC/MVS monitors inbound allocate requests for those for which a server has registered. APPC/MVS places such allocate requests on structures called allocate queues. Servers can retrieve allocate requests from allocate queues for later processing as needed. A server can register any number of times, each time specifying a different combination of selection criteria (TP name/local LU name, plus filters). APPC/MVS creates a separate allocate queue for each unique registration.