Im trying to get my head around why old bp is pushed and bp sp are altered after function calls does this code look okay?

push bp 
	call showstack ;
        |bp|<--bp sp
        pop bp;     |empty|
        mov sp, bp ;should this not be mov bp,sp or is old bp when popped put int the current bp? reg
 	
      


showstack:
         
	push 57h ;|bp|nla|57h
        mov bp,sp ;|bp|nla|57h <-----bp and sp after this mov
        mov al, [bp]  ;  
    	mov ah, 0x0E	; video function 0Eh (print char)
	mov bx, 0x0007	; color
	int 0x10
	
  	retn