Terminate but stay resident (INT 21h, 31h)

        Entry:
          AH = 31h
          AL = exit code
          DX = program size, in paragraphs
        Return:
          Never!

        This function call terminates the current process and attempts
        to set the initial allocation block to the number of paragraphs
        in DX. It will not free any other allocation blocks belonging
        to that process.