The ADDRESS OF special register references the address of a data item in the linkage section, the local-storage section, or the working-storage section.
For 01 and 77 level items in the linkage section, the ADDRESS OF special register can be either a sending item or a receiving item. For all other operands, the ADDRESS OF special register can be only a sending item.
The ADDRESS OF special register is implicitly defined as USAGE POINTER.
A function-identifier is not allowed as the operand of the ADDRESS OF special register.