Before executing an application program under IMS, you must describe that program and its use of logical terminals and logical data structures through a program specification block (PSB) generation. The PSB generation statements supply the identification and characteristics of the IMS resources to be used. These program communication blocks (PCBs) represent message destinations and databases used by the application program. In addition, there must be a statement supplying characteristics of the application program itself. There must be one PSB for each message, batch, or Fast Path program. The name of the PSB and its associated application program must be the same in a telecommunications system.

If you require only an I/O PCB and a single, modifiable alternate PCB, you can use a generated PSB (GPSB) to describe the resources required for your application program. GPSBs can be used in any online environment, and are typically used in DCCTL application programs. You do not need to perform PSBGEN for GPSBs.

Related Reading: Refer to IMS Version 7 Installation Volume 2: System Definition and Tailoring, GC26-9430 and IMS Version 7 Administration Guide: Transaction Manager, SC26-9421 for more information on GPSBs.

In this Chapter:

• "Input and Output" in topic 1.2.1

• "PSBGEN Procedure" in topic 1.2.2

• "Utility Control Statements" in topic 1.2.3

• "Output Messages and Statistics" in topic 1.2.4

• "Examples" in topic 1.2.5

Subtopics:

• 1.2.1 Input and Output
• 1.2.2 PSBGEN Procedure
• 1.2.3 Utility Control Statements
• 1.2.4 Output Messages and Statistics
• 1.2.5 Examples

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