What is resource definition? - IBM - AS/400

Resource definition is the process by which you tell your system which resources to use, what their properties are, and how CICS can use them. CICS/400 must know the configuration of terminals and logical units in the network. To process transactions, it must be able to load and execute the appropriate program for each expected transaction type. To recover data in the event of a problem with the system, it must be able to locate temporary storage queues.

Gathering preliminary information
Before you start, you need to gather all the information necessary to define the resources to the system, based on business requirements, information provided by either the application developer or the packaged software application. In addition, you have to create the underlying OS/400 objects required by the applications.

To understand the requirements, you need the answers to a number of questions. For instance:

• What is the system ID (SYSID) or control region name (CTLRGN) of the system you are setting up?
• Which functions and transactions is each user going to use on the system?
• Will the system communicate with other systems?
• Does the system require directly-connected printers?
• What applications are going to be run on the system?
• Where are the program objects and the map sets going to be located?
• Which files do the applications use?
• Are the files recoverable?
• How does the application use those files?
• What kind of access is needed for the files? Keyed-sequence, random, or sequential?
• Do the applications require transient data, temporary storage, or both?
• Does the system need to use any of the supplied transactions?
• What are the names of the resources and their corresponding OS/400 objects?

Resource definition tables
Resources are stored in resource definition tables. CICS/400 uses the information in the tables to control the interactions between, for example, programs and terminals, transaction identifiers and programs, between different CICS systems, and so on.

There are 11 different resource definition tables: some, like the system initialization table (SIT), need to be defined before CICS can be executed; but others, like the conversion vector table (CVT), need not be defined for CICS to function successfully. The resource table names are abbreviated to three-letter acronyms. Throughout the rest of this chapter, the acronym is used to refer to the tables, unless otherwise stated. Resources may reside on the local CICS/400 system, or on a remote CICS system. All resources residing on other CICS systems, and the systems themselves, should be defined in the appropriate resource definition table, before CICS can access the systems and use those resources.