CICS stands for "Customer Information Control System". It is a family of mixed-language application servers that provide online transaction management and connectivity for applications on IBM mainframe systems under z/OS and z/VSE. CICS is middleware that sits between the z/OS IBM mainframe operating system and business applications. It is used widely in the brokerage and banking, debit and credit card processing, insurance, communications, airline, and hospitality industries, and in many Fortune 500 companies throughout the world.
CICS is designed as middleware and supports rapid, high-volume online transaction processing. A CICS transaction is a unit of processing initiated by a single request that may affect one or more objects. This processing is usually interactive (screen-oriented), but background transactions are possible. A CICS transaction is a set of operations that perform a task together. Usually, the majority of transactions are relatively simple tasks such as requesting an inventory list or entering a debit or credit to an account. A primary characteristic of a transaction is that it should be atomic.
As an application server, CICS hosts applications that are written in COBOL, C, Java, and PHP. Regardless of the programming language used, CICS functions as middleware that specializes in rapidly and dependably processing large payloads of online, real-time transactions when it is invoked by an application.
The latest version of CICS, V5.6, offers a choice of APIs, frameworks, editors, and build tools for developers. CICS Transaction Server (CICS TS) sits at the head of the CICS family and provides services that extend or replace the functions of the operating system. These services can be more efficient than the generalized operating system services and also simpler for programmers to use, particularly with respect to communication with diverse terminal devices.
In summary, CICS is a middleware that provides online transaction management and connectivity for applications on IBM mainframe systems under z/OS and z/VSE. It is widely used in various industries and supports rapid, high-volume online transaction processing.
