Joined: 06 Jan 2004
Please post the threads in the respective forums.so that it would be very easy to refer.Even you can get answer quickly for your queries.
Coming to your question:
Using Symbolic parameter you can supply values to that later.In general we will be using notify=&sysuid.
A symbolic parameter is a variable name that can take on various assigned values. A symbolic parameter can be assigned anywhere within the PROC.The major strength of a cataloged PROC is its flexibility through the use of symbolic parameters.
where as Overiding in the sense you are over riding the already present parameters.
An overriding or added DD statement must have the form:
//procstepname.ddname DD parameters
where "procstepname" identifies the procedure step the user is overriding and "ddname" is the DD statement in that procedure step. The following DD statement is an example:
//STEP2.C7950R01 DD UNIT=TAPE
here in the above example you are overriding the value if already present
or adding if not.
Even you can nullify the values by overriding them
//STEP3.OUTPUT DD UNIT=,SPACE=
Hope you understand