MC68HC08AS20 Datasheet, PDF (52/386 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

During a subroutine call, the CPU uses two bytes of the stack to store
the return address. The stack pointer decrements during pushes and
increments during pulls.
NOTE:
Be careful when using nested subroutines. The CPU could overwrite
data in the RAM during a subroutine or during the interrupt stacking
operation.
Advance Information
52
MC68HC08AS20 —Rev. 4.1
Freescale Semiconductor