Radio Shack TRS-80 Model 4 - Page 321

Conditional Decisions
U sing IIIF, IlEND, IIELSE
The logical compilation macros (lIIF, IIEND, and IIELSE) are used to
establish logical "blocks"
in a JCL file. When a JCL file is being
compiled, these blocks are evaluated
as either true or false.
The
IIIF macro followed by a token determines if the block is true or
false.
To set a token true, specify
it on the DO command line. To set a
token false, do NOT specify
it on the DO command line.
These JCL macros produce the following results:
1) If token is true. . . 2) If token is false ...
IIIF tof,en
Include these lines.
IIEND
IIIF tof,en
I~nore these lines.
IIEND
3) If token is false, perform the alternative ...
IIIF tof,en
I~nore these lines.
IIELSE
Include these lines.
IIEND
With this type of logical decision capability, you can create a JCL file
and then pick a course of action
by typing in a "DO filespec"
command with different tokens.
Examples
Consider the following JCL file named START/JCL.
• START/JCL for pro~ram start-up
SET *FF to FORMS/FLT
FILTER *PR
*FF
IIIF PRl
FORMS (CHARS=80)
IIELSE
FORMS (CHARS=13:)
IIEND
Assume that these are the first lines in a JCL file that begins
execution of
an applications program.
To make the
IIIF PR1 test as true, issue the following DO command:
DO START (PR1) (ENTER)
The 80 characters per line is selected.
A-16