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What is APPC?

An APPC/OS/390 implementation from a single host processor consists of:

The purpose of each of these components is described following:

APPC Started Task

Used to manage conversations between TPs.

ASCH Started Task

Used to manage sets of transaction initiators (the address spaces that run the TPs on inbound requests); also called the transaction scheduler.

LUs

Nodes or other points of entry into the network. Each Transaction Program (TP) is associated with a single LU.

TPs

Referenced on the EXEC statements found in the TP profile JCL stream; can be written in COBOL, C, PL/I, FORTRAN, ASSEMBLER, or REXX.

TP profile data set

VSAM KSDS data sets used to describe the TPs available from a single LU or set of LUs reached by an inbound transaction request. It contains the TP class and the JCL used to run the TP in the transaction initiator. TP profile data sets are administered using either a batch utility (ATBSDFMU) or an interactive ISPF dialog.

Side‑information file

VSAM KSDS used by the APPC address space to translate symbolic destination node names to the appropriate VTAM LU/TP names. There is one side‑information file per system.