Chapter 2.   Concepts and Components CICS BTS comprises a set of new CICS commands and services that allow easier implementation of entire business transactions under system control.   The distinction between a business transaction and a CICS transaction is that a business transaction normally is of a longer lived nature, such as hours, days, even weeks.   A business transaction lives, for example, from the time some kind of business contract is agreed upon until the final payment for delivered goods is booked and completed.   A CICS transaction, on the other hand, normally should take seconds or fractions of a second to complete. The concept of expanding the CICS services is based on the need to portray complex business processes so that the program code only implements individual business steps or business tasks to be supported.   That is, each element of a business process, the business process step, is analyzed and designed independently by looking at the ways the element interacts with other elements and outside inputs.   With the new capability of CICS, it is possible to implement the tasks following the analysis of the business process and each individual business step.   The outside inputs can be accepted from non-CICS BTS transactions as input events.   This event then can be processed by the business logic in an activity. The single elements of a CICS BTS process are implemented as activities.   These comprise the solution of a relatively small business task or tasks.   If more than one business task is to be implemented by one activity, the decision which task has to be executed in a given activation of the activity can be done by the activity analyzing its data-container.   This concept provides function hiding within each activity. With this new view of CICS programming comes a set of new concepts, which we describe in this chapter. 2.1   CICS BTS Terminology In this section we introduce the CICS BTS terminology. Ÿ    INITIAL  REQUEST: A CICS transaction that starts a CICS BTS process. Ÿ    PROCESS: A collection of one or more CICS BTS activities.   It has a unique 36-character name by which it can be referenced and invoked.   Typically, a process is an instance of a business transaction. A process can be categorized by the process type.   A process is controlled by a program that represents the root activity.   A process is not always active, but it stays alive in CICS until it is entirely completed, that is, until all its activities have completed. A process is represented as a block of storage containing information relevant to its execution.   It is also associated with at least one additional block of information called an activity instance.   When not executing, a process and its activity instances reside in a repository. The CICS BTS repository data set is a VSAM KSDS data set that holds state information about the CICS BTS processes as well as application data Copyright IBM Corp. 1999 7