What is an APPC/MVS Transaction Program?

APPC/MVS transaction programs are application programs running on MVS™ or TSO/E that use special calls to communicate with partner programs on the same MVS system, other MVS systems, or other operating systems in a System Network Architecture (SNA) network. To communicate, the transaction programs hold APPC conversations; in the conversations, they exchange information using specific calls and follow established conversation protocols.

APPC/MVS transaction programs can be involved with TSO/E in the following ways:

You can write transaction programs in REXX using the LU62, CPICOMM, or APPCMVS host command environments to issue APPC calls to a partner transaction program. For more information on these host command environments, see z/OS TSO/E REXX Reference.
Programs on MVS, including APPC/MVS transaction programs, can use the TSO/E environment service (IKJTSOEV) to create a TSO/E environment outside of TSO/E. The programs can then use TSO/E services as described in z/OS TSO/E Programming Services.
Programmers can use the TSO/E TEST and TESTAUTH commands to test certain transaction programs. The commands can be used with inbound transaction programs—those that are initiated in response to inbound conversation requests from their partner transaction programs. These inbound transaction programs are specified on the TEST or TESTAUTH commands and, when requested by their partner programs, are initiated for testing under TSO/E. Outbound APPC/MVS transaction programs are those transaction programs that are not initiated by inbound conversation requests. You can test these transaction programs as ordinary programs using TEST or TESTAUTH (that is, do not specify the TP, LU, BASELU, or KEEPTP keywords). For more information about testing transaction programs on TSO/E, see z/OS TSO/E Command Reference.

For more information about APPC/MVS transaction programs in general, their benefits for cross-system communication and how to write and use transaction programs, see z/OS MVS Programming: Writing Transaction Programs for APPC/MVS.