assume cs:code

stack segment

    db 16 dup(0)

stack ends

code segment

    start:  mov ax, stack

            mov ss, ax

            mov sp, 16

            mov ax, 0

            call far ptr s

            inc ax

        s:  pop ax

            add ax, ax

            pop bx

            add ax, bx   

    mov ax, 4c00h

    int 21h

code ends

end start