What does CICS do?

CICS controls online DB/DC application programs. But what does this mean? In fact, it means that CICS is a program that does a lot of work on your behalf. CICS handles interactions between terminal users and your application programs. An interaction may consist of one or more requests from, and responses to, a terminal user in the course of a single job by that user.

CICS provides:

The functions required by application programs for communication with remote and local terminals and subsystems

Control of concurrently running programs serving many online users Facilities for accessing databases and files, in conjunction with the various IBM database products and data access methods that are available

The ability to communicate with other CICS systems and database systems, both in the same computer and in connected computer systems.

IBM has left things as open as possible to allow customers to produce the system they need. It's up to your systems and applications designers (which could mean you, of course) to choose what they want from the various CICS facilities, and to build whatever kind of user interface that best suits the end users. So, although you still have to provide the application programs that the end users actually run, CICS makes it much easier. Your programs gain access to the CICS facilities they need by straightforward, high-level, commands.