Structure of JCL Statements

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JCL Statement Structure:

• JCL statements are coded in 80 bytes.
  
  
• 72 of the 80 columns are available to code JCL.
  
  
• Last 8 columns are reserved for an optional sequence number.
  
  
• Each JCL statement is divided into several fields.

Syntax or Format:

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Let's us see each field in detail,

1. Identifier Field:

• The identifier field identifies a record as a JCL statement.
  
  
• For most JCL statements, the identifier field occupies the first two character positions and must contain two slashes (//). There are two exceptions.
  
  
• First, the delimiter statement has a slash in column 1 and an asterisk in column 2 (/*).
  
  
• Second, the identifier field for a comment statement is three characters long: The first two columns contain slashes and the third contains an asterisk (//*).

Example:

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2. Name Field:

It follows identifier field. The name field associates a name with a JCL statement.

• It is not mandatory everywhere; but it is always required on a JOB statement, where it supplies a name for a job.
  
  
• A name field must begin in column 3, right after the identifier field.
  
  
• It consists of one to eight characters, which may be letters, numbers or national characters (#, @, and $) Also, the first character of a name should be a letter or a national character.

Example:

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Name field - Incorrect values:

Here the Name field is of length 9 characters hence we get this error:



Note here the Name field begins with a numeric value. Hence we get this error.

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3. Operation Field:

The operation field follows the name field and it specifies the statements function.

• JOB, EXEC, and DD are the different operation fields.
  
  
• This field can be coded anywhere in the JCL, but it should be separated from the name field by at least one blank.
  
  
• However, conventionally, the operation field should be started in column 12.

Example:

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4. Parameters Field:

The parameters field begins at least one position after the end of the operation field and can extend into column 71:

1. Within the parameters field, we have to code one or more parameters that supply information that influences how the statement is processed.
   
   
2. When a parameters field consists of more than one parameter, the individual parameters should be separated with commas.
   
   
3. MVS assumes that the parameters field is complete when it encounters a space so do not include a space by accident. If you need to include a space as part of a parameter value, the parameter value must be enclosed in apostrophes.

Example:

There are two types of parameters:

1. Positional
2. Keyword

We will be discussing about each parameters in next chapter.

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5. Comments Field:

Following the parameters field, you can code brief comments in the comments field.

• The comments field begins in the position after the space that marks the end of the parameters field and ends in column 71.
  
  
• MVS ignores what is coded here, so you can record any comments you wish.
  
  
• You can also use an entire line as a comment.
  
  
• For this, you need to code //* starting from column one of the JCL record.

Example:

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How to continue JCL statements?

When it is not possible to fit all the parameters on a single 80-character line, the statement can be continued onto one or more additional lines by following the below steps:

• Break the parameter field after the comma that follows a parameter or sub-parameter.
  
  
• Code slashes in columns 1 and 2 of the following line.
  
  
• Code the next parameter beginning anywhere in columns 4 through 16.

Example:

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Video Tutorial: JCL Statement Structure

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