THEN Statement

Purpose

The THEN statement is an essential part of JCL conditional processing. It follows an IF statement and marks the beginning of a block of JCL statements that will be executed when the IF condition evaluates to true.

Syntax

1
2
3
4
5
//[name] IF (condition) THEN
//         statements to be executed if condition is true
[//         ELSE
//         statements to be executed if condition is false]
//         ENDIF

Key Points

• THEN is always required after an IF statement
• It must appear on the same statement line as the IF
• It introduces the statements to be executed when the condition is true
• The THEN block continues until an ELSE or ENDIF statement is encountered

Examples

Basic IF/THEN Structure

1
2
3
4
//         IF RC = 0 THEN
//STEP2    EXEC PGM=GOODRUN
//PRINT    DD SYSOUT=A
//         ENDIF

IF/THEN/ELSE Structure

1
2
3
4
5
//         IF STEP1.RC < 8 THEN
//STEP2    EXEC PGM=REGULAR
//         ELSE
//STEP2    EXEC PGM=RECOVER
//         ENDIF

Nested IF/THEN

1
2
3
4
5
6
7
8
//         IF &SYSDAY = 'FRIDAY' THEN
//           IF &SYSTIME > '17:00' THEN
//             SET BACKUP='FULL'
//           ELSE
//             SET BACKUP='INCR'
//           ENDIF
//STEP1    EXEC PGM=BACKUP,PARM='&BACKUP'
//         ENDIF

Notes

• The THEN keyword must appear on the same JCL statement as the IF condition
• The statements controlled by the THEN clause must follow on subsequent lines
• JCL statements in the THEN block can include any valid JCL, including EXEC, DD, and SET statements
• If the condition is false, execution skips to the ELSE clause or ENDIF statement
• The name field in the IF/THEN statement is optional and is typically omitted
• No special continuation is needed for the THEN keyword

Common Mistakes

• Putting THEN on a separate line (must be on the same line as IF)
• Forgetting the corresponding ENDIF statement
• Incorrect nesting of multiple IF/THEN blocks
• Using END instead of ENDIF to close the block

Related Concepts

• IF Statement - Begins the conditional block
• ELSE Statement - Optional alternative path
• ENDIF Statement - Required to end the conditional block
• Conditional Execution - Overall concept in JCL
• COND Parameter - Alternative method for conditional execution

Related Pages

• IF Statement - Contains conditions for THEN
• ELSE Statement - Alternative execution path
• ENDIF Statement - Terminates an IF/THEN structure
• SET Statement - Commonly used in THEN blocks
• Symbolic Parameters - Often referenced in conditions