JCL is Job Control Language.

Statement is an instruction that we are coding in JCL
Types of Statements
i. [Normal] Statement
ii. Comment Statement
iii. Delimiter Statement
iv. Null Statement

[Normal] Statement:

-> Every Normal Statement should begin with //
-> Every statement starts at 1st coloumn

Statement Structure:

I – Identifier field
N – Name field. Name field should start from 3rd column. Name can contain
a maximum of 8 charecters. The first charecter in name must be an
alphabet or National charecter(@,#,$). Name field can contain only
alphabets numbers and @, #, $.
O – Operation field. It starts after name field by leaving atleast one
coloumn. But practice is to write from 12th column.
P – Parameter field. It starts after Operation field by leaving atleast one
blank. There are tow types of parameters. Positional and Keyword.
Positional parameters must be coded first and Keyword parameters later.
Positional parameters must be written in the same order they appear
first in the JCL. All parameters are to be seperated by a comma except
the last. Absence of positional parameters must be indicated by a comma.
Sub parameters in the keyword parameters can be positional.
C – Comment field. Comments can be written after the parameter filed by
leaving one space.

Statements upto Parameter field should not exceed 71 column. System ignores anything written beyond 71 column. Comments should not exceed 80th Column.

Comment Statement : Begins With //*. Whatever written after //* is ignored by
the system.

Delimiter Statement : Begins with /*. It indicates the end of instream data.

Null Statement : If we just write // and nothing else, it indicates the end of
JCL. Execution of JCL is terminated when Null statement is
encountered.