Mainframe, MVS and zOS Discussion

Interview question:

A job is executing 2 procs in its two steps.
Jobstep J1 exec P1 proc
Jobstep J2 exec P2 proc

In Proc P1, I am creating a GDG A.B.C(+1). In Proc P2, I want to refer to the same version. So In P2 do I refer to (+1) version or (0) version. And why.

This is specifically addressed in the JCL reference manual. The answer is that all references to a GDG generation in a single job are the same -- if you use (+1) in one step, you will use (+1) in all subsequent steps in that job.