DD statement with parameter explanation...

DD STATEMENT :

The DD statement (Data Definition), is used to identify the source of input 
and the placement of output information


Syntax  ->  //ddname  DD  < positional / keyword parameters >

            ddname must be unique in the job

      
            Positional parameters -  *
                                                       DATA
                                                       DUMMY
                                                       DYNAM

            Keyword Parameters   -  DSN
                                                       DISP
                                                       UNIT
                                                       SPACE
                                                       DCB
                                                       VOLUME