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CICS stands for Customer Information Control System. CICS was developed in 1968 by IBM. CICS allows users to develop and execute online application in an MVS environment. CICS has become the most commonly used server for Internet applications. CICS is a transaction processing system which is also called as Online Transaction Processing (OLTP) Software. CICS is a data communication system that can support a network containing hundreds of terminals.

Audience

This tutorial is designed for software programmers who would like to understand the concepts of CICS starting from scratch. This tutorial will give you enough understanding on CICS from where you can take yourself to higher levels of expertise.

Prerequisites

Before proceeding with this tutorial, you should have a basic understanding of COBOL programming. A basic knowledge of MVS and TSO/ISPF subsystem will help you grasp the concepts of CICS better.

Overview

CICS is a DB/DC system which is used in online applications. CICS was developed because batch operating system can execute only batch programs. CICS programs can be written in COBOL, C, C++, Java, etc. These days, users want information within seconds and in real time. To provide such quick service, we need a system which can process information online. CICS allows users to communicate with the back-end system to get the desired information. Examples of online programs include online banking system, flight reservation, etc. Following image shows the components of CICS and how they are inter-related −

cics overview

Functions of CICS

The main functions performed by CICS in an application are as follows −

  • CICS manages requests from concurrent users in an application.
  • Although, multiple users are working on CICS system but it gives a feel to user that he is the single user only.
  • CICS gives the access to data files for reading or updating them in an application.

Features of CICS

The features of CICS are as follows −

  • CICS is an operating system in itself, as it manages its own processor storage, has its own task manager which handles execution of multiple programs, and provides its own file management functions.
  • CICS provides online environment in batch operating system. Jobs submitted are executed immediately.
  • CICS is a generalized transaction processing interface.
  • It is possible to have two or more CICS regions at the same time, as CICS runs as a batch job in the operating system at the back-end.

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