To be able submit a job using another user acid via USER= on the job card, the user must be authorized to that acid, which can be done in 2 ways.
1. Permit the user to the other acid.
TSS PERMIT(USERA) ACID(USERB).
USERA is now allowed to submit jobs under USERBs acid.
2. Give the user NOSUBCHK attribute.
TSS ADD(USERA) NOSUBCHK
This allows USERA to submit a batch job using anyone's acid.
NOSUBCHK is frowned upon by auditors and should be given out sparingly.
This type of security is called Cross Submit Authorization Checking.