You might put rest of the steps inside a IF construct which allow the execution of the stpes only when RC=4 of step5.I am planning to terminate the jcl at the end of step 5 here, if i get a return code of 4.
If return code is zero, i shall continue execution of the jcl.
By the way, if you get RC=4 in step5 - are you able to abend the job? I'm little unsure about the "context" of word abend in your explanations...