Here's an important thing to remember about big businesses: when downtime occurs, it impacts them in a big way. Downtime is, quite simply, an absolute disaster. And when we talk about "big business" we're not just talking about your run-of-the-mill corporation, either. We're talking about Fortune 500 -- the largest corporations in the world. Now, because they cannot afford downtime, these mega corporations require "mission-critical" transaction systems to run on powerful mainframes. This is where Customer Information Control System (CICS) comes in. Many of these companies -- up to 90 per cent of the world's Fortune 500 companies, it has been estimated -- use CICS for their rapid, high-volume online processing needs, with the help of terminal emulation software to access the CICS servers.

What is CICS?

CICS is a transaction processing system that is capable of handling enormous numbers of transactions -- in some cases, we're talking thousands of transactions per second. CICS is not just a transaction handler, however -- it is also capable of handling job submissions, domain management, catalogue updating and application bridging.

CICS applications are usually run by submitting a transaction request. The transaction's execution involves running at least one application program that can implement the necessary function. In CICS documentation, you'll find CICS application programs simply referred to as "programs", while the entire process is referred to as a "transaction".

History of CICS

CICS was originally developed in the U.S. in 1969 for mainframe systems on the smaller end of the scale, but it now finds its use in some of the largest businesses and governments in the world. Early on, it was delivered to Amoco with Teletype Model 33 ASR support, and resulted in the whole OS/360 operating system crashing -- including even non-CICS application programs.

It was then redesigned and rewritten by Amoco and returned to IBM for free distribution. Just a few years later, CICS had generated tens of billions of dollars in hardware revenue for IBM and became its most commercially successful mainframe software product.

Today, it runs mainly on IBM's 64-bit z/OS, but it is capable of running on other operating systems as well, including z/VSE, OS/2 and i5. It can also run on third-party operating systems, such as Windows, AIX, HP-UX and Oracle's Solaris. Access is with the use of terminal emulation software such as a Complete 3270 Emulation for Windows® or software such as IBM's CICS Explorer.

How is CICS Pronounced?

One question that can't seem to be resolved around the world is how to pronounce the CICS acronym. While this could probably be resolved by simply pronouncing each letter of the acronym individually, efficiency dictates that pronouncing it as one syllable is an easier way to go.

In most English-speaking countries, for example, it is pronounced like the word "kicks".

Head to other parts of the world, however, and it will likely be pronounced differently. In Italian, for example, it would be pronounced like "chicks". In German, it would be pronounced like "zicks". In Portuguese-speaking countries such as Brazil and Portugal, it would be pronounced "sicks". And in Spain, it would be pronounced "thicks".