What is a CICS transaction and how is it different from a program?

In CICS, a transaction is a unit of work that is executed by a user on a mainframe system. It typically represents a specific task or operation that needs to be performed, such as updating a database or processing a customer request.

A CICS program, on the other hand, is a set of instructions written in a programming language like COBOL or PL/I that dictates how a transaction should be carried out. While a transaction represents the high-level task, a program provides the detailed logic and flow control to accomplish that task.

So, in summary, a CICS transaction is the overarching entity that encompasses the execution of a specific task, while a program is the code that defines the steps and procedures to be followed in carrying out that task.