Yes, pretty much.
The machine is not your machine. It is used by many people. If your program sits there "waiting" for a while, what are you going to do?
So, have the job NOTIFY you. Or send you an e-mail. Then you/whoever can start the next bit. Remember, that can even be hours later, depending on numerous factors.
Do some re-thinking remembering that a Mainframe is a machine for grown-ups, not something you just get to play on without regard to other, quality, teamwork, rationality, etc, etc, etc,