REXX Programming under TSO/ISPF Training

An understanding of programming at a conceptual level and a good knowledge of TSO and its commands. A superficial knowledge of ISPF/PDF is insufficient for those who wish to gain full value from this course.

• describe the concepts and structure of the REXX language environment
• write and debug REXX programs executing in the TSO environment
• use the tracing and debugging aids effectively
• use the loop control and decision making instructions
• identify and put into practice the most commonly used REXX built in functions
• parse data strings
• use TSO commands and functions within REXX EXECS
• manage I/O using data stacks and stems
• use sub-routines and functions.

Introduction to TSO REXX

Executing REXX EXECs; elements of the REXX language: Clauses, Tokens, Labels, Assignments, Instructions and Commands; constant and variable symbols; Simple, Compound & Stem variable symbols; operators for concatenation, arithmetic, comparison & logical operations.

Tracing and Debugging

Using TRACE instruction for debugging; using immediate commands HI, HT, TS and TE; use of EXECUTIL; interpreting TRACE output.

Parsing Strings

Parsing variables and strings; basic parsing techniques; special templates; place holders, literal patterns and numeric patterns.

Control Instructions

Decisions: IF, THEN, ELSE, SELECT, WHEN, OTHERWISE; creating and controlling loops: DO WHILE, UNTIL, FOREVER, LEAVE, ITERATE; introduction to sub-routines.

Sub-routines and Functions

Internal and external sub-routines; how to create internal and external functions; passing arguments and results to and from sub-routines and functions; CALL; RETURN; EXIT; PROCEDURE; RESULT.

REXX Built-in Functions

Introduction to REXX supplied built in functions; how to use the most useful ones: ARG, DATE, TIME, DATATYPE, LENGTH, POS, WORDS, LEFT, RIGHT, STRIP, SPACE, COPIES and WORD.

Data Stack Management

LIFO and FIFO stacking; avoiding the stack; writing to the stack: PUSH and QUEUE; reading from the stack: PARSE PULL; creating and managing extensions to the stack: MAKEBUF, QBUF and DROPBUF; interrogating the stack: QUEUE, QELEM; creating and managing private stacks: NEWSTACK, DELSTACK and QSTACK.

Using TSO Commands & Functions

Using TSO commands and functions: SYSDSN, LISTDSI, MSG, OUTTRAP, PROMPT and SYSVAR; reading and writing datasets with EXECIO.