How to resize 3 parts of a frame (of Beamer)? [closed]

Question

I have split a slide into 3 parts: a block on the top, and 2 pictures on the bottom side by side:

\begin{block}{concretization}
  \renewcommand{\arraystretch}{1.5}%
  \resizebox{\textwidth}{!}{
  ...
  }
\end{block}      
\begin{columns}
\begin{column}{.35\textwidth}
  \begin{framed}
    \hspace*{-1em}{
      \resizebox{!}{0.48\textheight}{
        \begin{tikzpicture}[thick, scale=0.6]
        ...
        \end{tikzpicture}}
    \end{framed}
  \end{column}
  \begin{column}{.48\textwidth}
    \begin{framed}
    ...
    \end{framed}
  \end{column}
\end{columns}

The problem is the pictures go beyond the bottom border of the slide. the combination of \begin{column}{.35\textwidth} and \resizebox{!}{0.48\textheight}{ is not good, What I want is to let the pictures occupy all the (vertical) space that the block leaves. Could anyone tell me how to decide the factor of scaling of the pictures?

Thank you very much!