Allocation-pipe connection definition
After a step starts execution, the allocation process passes all pipe allocation requests to the Pipe Handler component of the Job Optimizer Pipes Subsystem.
The pipe is defined when the first participant performs allocation by using JCL at step initiation or by using dynamic allocation during step execution.
After allocation has been performed successfully, the pipe is defined and the participant is connected to the pipe. Subsequent allocations to the same pipe name by other participants create additional connections to this pipe.
The allocation requests of the pipe participants can be synchronized. Participants wait during allocation until all required participants perform allocation to the pipe.
If a reader that is allocating the pipe does not provide all DCB attributes (LRECL, RECFM, BLKSIZE), the allocation process is delayed after the pipe/participant connection is defined until a writer opens the pipe and supplies all of the DCB attributes. The reader is allowed to continue and uses the DCB attributes that have been retrieved from the pipe.
Information about all of the pipes that have been defined in the system (or in the entire Parallel Sysplex environment if working in Global mode) is kept in the Pipe list. The Pipe list contains a Pipe List Entry (PLE) for each pipe with information about the pipe and all of its participants. A pipe is defined by creating a PLE in the Pipe List.