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Introduction to CL Programming

Why  write a CL program.

  • A CL program consists of a series of CL commands that you can compile and run as a group.

  • You can write CL programs that directly access system level operations.

 

How to create a CL Program.

  • Type all the needed CL commands into a source member.

  • Compile the CL program, creating a program object

Advantage of CL Program

  • CL programs are written to control the flow of work in a job

  • Compiled CL program leads to faster execution

  • CL provides programming language constructs like                              

         

          Arithmetic operators

         Logical Operators

         Handling Screens

         Db I/O  opearations

  • No syntax checking done at runtime but at compile time

Rules To declare variable

  • Variable names should begin with ‘&’ followed by as many as 10 characters

  • Character string (Max 9999 chars)

  • Packed decimal (15 digits with as many as 9 decimal positions)

  • Logical value (0 or 1)

Declare Variables and Files

     Variables

  • Parameters used in CL programs can be expressed as variables, constants or expressions

  • This should precede all commands except PGM Command

  • The variable declared should start with ‘&’

 

  Syntax:   DCL  VAR(&variable-name)

  Example:

   DCL VAR(&NAME1)  TYPE (*CHAR)  LEN(10)

           DCL  VAR(&TELE) TYPE (*DEC)  LEN(2  0) VALUE(10)

          Syntax :

  DCL  VAR(variable name)  TYPE    *DEC     LEN(LENGTH)  VALUE (initial-value)

                                                      *LGL

                                                      *CHAR

 

    File

  • Files may have one or more record formats and fields within it.

  • During CL program compilations, all fields and records are implicitly defined by DCL statements.

  • They are automatically available for use in CL Programs

 

Example:

  DCLF FILE(lsslib/filea)

                                                                                     

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