Return specifications

For the IRXEXEC routine, the contents of the registers on return are:

Register 0: Address of the environment block.
If IRXEXEC returns with return code 100 or 104, register 0 contains the abend and reason code. Return codes describes the return codes and how IRXEXEC returns the abend and reason codes for return codes 100 and 104.
Registers 1-14: Same as on entry
Register 15: Return code