stack

stack.tex

\documentclass[border=2pt]{standalone}    
\usepackage{tikz}
\begin{document}    
\begin{tikzpicture}
  \newcounter{shifty} \setcounter{shifty}{0}
  \foreach \n/\w in {A/1,B/2,A/1,A/1,B/2}{
    \node[yshift=\theshifty cm,draw,minimum height=1cm,minimum width=\w cm,anchor=west,outer sep=0pt]{\n}; 
    \draw[yshift=\theshifty cm,thick] (0,.6cm)--(0,-.6cm);
    \addtocounter{shifty}{\w}
  }
\end{tikzpicture}      
\end{document}