CICS TCP/IP components

In terms of CICS® operation, the CICS TCP/IP feature is a task-related user exit (TRUE) mechanism known as an adapter. The adapting facility that it provides is between application programs that need to access TCP/IP and the manager of the TCP/IP resource.

CICS TCP/IP has the following main components:

The stub program is link-edited to each application program that wants to use it. It intercepts requests issued by the calling application program and causes CICS to pass control to the TRUE.
The TRUE mechanism enables programs to pass calls to the subtask and to the TCP/IP address space.
CICS TCP/IP supports two methods for accessing TCP/IP
- The MVS™ subtask translates commands for accessing TCP/IP into a form acceptable to the TCP/IP resource manager and then passes control to the resource manager. The subtask also handles the MVS waits incurred during socket calls.
- Using CICS Open Transaction Environment (OTE). The TRUE mechanism accesses TCP/IP directly, not requiring an MVS subtask for blocking commands.
The Administration Routine contains the EXEC CICS ENABLE and DISABLE commands that are used to install and withdraw the TRUE program.
The Configuration System configures the interface and its listeners.