Continuation

Key Characteristics

• • JCL Continuation: For Job Control Language (JCL), a comma (,) placed in column 71 of a statement indicates that the statement continues on the next line. The continuation line must begin with // in columns 1-2 and the continued operand typically starts in column 16.
  • COBOL Continuation: In COBOL, string literals can be continued by placing a hyphen (-) in column 7 of the continuation line and enclosing the continued part of the literal in quotes. Non-numeric literals can also be continued without a hyphen if the previous line ends with a quote and the new line starts with a quote, effectively concatenating them.
  • Assembler Continuation: Assembler language uses a non-blank character in column 72 of a statement to signify continuation to the next line, which typically starts in column 16.
  • Fixed-Format Dependency: Continuation rules are intrinsically linked to the fixed-format nature of many mainframe languages, where specific columns have predefined meanings and line length limits are enforced.
  • Compiler/Interpreter Handling: The respective compilers, assemblers, or JCL interpreters are designed to recognize these continuation markers and logically reassemble the fragmented statement into a single entity for processing.

Use Cases

• • Long JCL Parameters: Extending PARM parameters on EXEC statements or DSN (Dataset Name) specifications on DD statements that exceed the standard 71-column limit.

  jcl
  //STEP1    EXEC PGM=MYPROG,PARM='INPUTFILE.DATASET.NAME.IS.VERY.LONG.AND.NEEDS.TO.BE',
  //         'CONTINUED.ACROSS.MULTIPLE.LINES.FOR.CLARITY.AND.READABILITY'

  • Complex COBOL Literals: Defining lengthy string constants or messages within MOVE or DISPLAY statements in COBOL programs.

  cobol
  01 MY-LONG-MESSAGE PIC X(100).
  ...
  MOVE 'This is a very long message that needs to be '
  -'continued across multiple lines in COBOL source '
  -'code for better readability and maintenance.' TO MY-LONG-MESSAGE.

  • Detailed Assembler Instructions: Writing complex macro calls or instructions with numerous operands in Assembler language that would otherwise exceed a single line.
  • SQL Statements in Host Programs: Embedding multi-line SQL statements within COBOL or PL/I programs, where the host language's continuation rules or specific SQL precompiler directives might apply.

Related Concepts