The stack pointer register (SP) may be directly updated by software using the MVC instruction. The SP points to the top of the stack and always contains a byte address. The programmer is responsible for ensuring the correct alignment of the SP. See Section 8.2.4.14 for more details on stack pointer convention that must be followed. The SP is shown in Figure 8-38.
Figure 8-38 Stack Pointer Register (SP) | LEGEND: R = Readable by the MVC instruction; W = Writeable by the MVC instruction; -n = value after reset |