All the integer registers and all the floating-point registers are global to all procedures in a running program. In addition to the registers, each function has a frame on the run-time stack. This stack grows downward from high addresses. Table A-2 shows the stack frame organization. A dummy word may be pushed ahead of the rightmost argument in order to preserve doubleword alignment.
All incoming arguments appear on the stack, residing in the stack frame of the caller.
An argument's size is increased, if necessary, to make it a multiple of words. This may require tail padding, depending on the size of the argument. All registers on a IA system are global and thus visible to both a calling and a called function. In other words, a called function must preserve these registers' values for its caller. Remaining registers belong to the called function.