What is really pointless - that is posting pages of bullshit text here, instead of trying to run your own multiple various test code, and to find out for yourself: what is what, and who is who.
This forum is already overloaded with beggars, who only ask for "help" (aka "do their job for them in full"), and either do not want, or are not able to find simple answers to primitive questions, such as "requirement to calculate (2 + 2) using only JCL tools".