Writing applications that use the IP CICS sockets API

This topic describes how to write applications that use the IP CICS® sockets API. It describes typical sequences of calls for client, concurrent server (with associated child server processes), and iterative server programs. The contents of the topic are:

The following setups for writing CICS TCP/IP applications are available:
- Concurrent server (the supplied listener transaction) and child server processes run under CICS TCP/IP.
- The same as 1 but with a user-written concurrent server.
- An iterative server running under CICS TCP/IP.
- A client application running under CICS TCP/IP.
Socket addresses
MVS™ address spaces
GETCLIENTID, GIVESOCKET, and TAKESOCKET commands
The listener program
CICS Open Transaction Environment considerations
Application Transparent Transport Layer Security (AT-TLS)

C language application programming describes the C language calls that can be used with CICS.

Sockets extended API provides reference information on the Sockets Extended API for COBOL, PL/I, and Assembler language. The Sockets Extended API is the preferred interface for new application development.

Note: Original COBOL application programming interface (EZACICAL) provides reference information on the EZACICAL API for COBOL and assembler language. This interface was made available in a prior release of TCP/IP Services and is being retained in the current release for compatibility. For the best results, however, use the Sockets Extended API whenever possible. It is described in Sockets extended API.