Abstract: A data processing system includes three resources, i.e., a memory, a general purpose register file having a plurality of elements and a stack having a top. The system further includes a first mechanism for making the top of the stack correspond to at least one of the elements in the general purpose register and a second mechanism for controlling the operation of the stack. When the element to which the top of the stack corresponds is specified in an instruction register of the system, the top of the stack is selected to be accessed by the first mechanism and the operation of the stack is controlled by the second mechanism.