Advanced Program-to-Program Communication (APPC) is an implementation of the Systems Network Architecture (SNA) LU 6.2 protocol that permits interconnected systems to communicate and share the processing of programs. Installations can use APPC to allow MVS™ systems to participate in a cooperative processing environment.

Application programs that use APPC communication calls to perform cross-system requests are called transaction programs. Transaction programs can communicate with other transaction programs that reside on local or remote systems. For example, an installation might create a transaction program and use APPC to access MVS services on a host, such as updating a large data base; the MVS transaction program could subsequently return messages or data.

APPC transaction programs can exploit certain JES2 facilities, such as printing, network job entry (NJE), and job submission. JES2 treats all SYSOUT produced by APPC transaction programs as spin data sets. APPC transaction programs do not run as JES2 jobs; instead, transaction programs are associated with APPC transaction initiators, which are long-running jobs that can sponsor many transaction programs.

Output from APPC will have the 'PROTected' indicator, but this has nothing to do with RACF® or other security servers. Also, the 'PROTected' indicator is not exclusive to APPC; it is found in OMVS and in other transactional environments where the transaction output is associated with the initiators such as ASCHINIT and BPXAS.

Because APPC work is treated differently from other JES2 work, you should be aware of the following processing considerations for SYSOUT data sets created by a transaction program: