What is a CICS application?

An application is a collection of related programs that together perform a business operation, such as processing a product order, or preparing a company payroll. CICS® applications execute under CICS control, using CICS services and interfaces to access programs and files.

CICS is a transaction processing subsystem. It provides services for you to run applications online, by request, at the same time as many other users are submitting requests to run the same applications, using the same files and programs. CICS manages the sharing of resources, integrity of data, and prioritization of execution, with fast response.

CICS applications are traditionally run by submitting a transaction request. Execution of the transaction consists of running one or more application programs that implement the required function. In CICS documentation, CICS application programs are sometimes called programs, and the term transaction is used to imply the processing that the application programs do.

The term transaction is now used extensively in the IT industry to describe a unit of recovery, which in CICS is called a unit of work. This is typically a complete operation that is recoverable; it can be committed or backed out as an entirety, as a result of programmed command or system failure. In many cases, the scope of a CICS transaction is also a single unit of work, but be aware of the difference in meaning when you use non-CICS documentation.