System control offsets to callable services
An alternative to loading or link-editing the service stub is to include in the code the system control offset to the callable service. For example, use decimal 52 for the offset of access (BPX1ACC).
When using the offsets, set the registers up as follows:
- Register 1
- To contain the address of your parameter list. Set bit 0 of the last address in the list on.
- Register 14
- To contain the return address in the invoking module.
- Register 15
- To contain the address of the callable service code.