Do not code TIME=0 on a JOB statement. The results are unpredictable.
Coding TIME=NOLIMIT is the same as coding TIME=1440.
Coding TIME=1440 is the same as coding
Coding TIME=MAXIMUM allows a job to run for 357912 minutes.
2. How will u decide what is the value should be coded in SPACE parameter?
And regarding Ur space parameter, Consider this example, a data set created with SPACE=(CYL,(5,1)) causes 5 cylinders to be allocated to the data set, and, if it needs more space, it can obtain 1 additional cylinder. Like wise it depends on the programmer to allocate the space according to the data which is handeled by the JCL or CODE.