How to undo the feasible breakpoints of `lstlisting`?

Question

Is there a way to prohibit pagebreaking at the beginning/end of an lstlisting environment?

I'm trying to keep together the following two pairs of lines:

• the first line of lstlisting and the line before that
• the last line of lstlisting and the line after that

But pagebreaking should be available (so using minipage is not a solution) - there are code snippets more than one page long.

As far as I know \end{lstlisting} implicitly adds a feasible breakpoint so it has to be undone to do this.

\documentclass{article}

\usepackage[a6paper]{geometry}
\usepackage{listings}

\begin{document}

\textbf{Keep the first two together}

\vspace{22\baselineskip}

\noindent Line Before
\begin{lstlisting}
First line
Middle lines
Middle lines
Middle lines
Last line
\end{lstlisting}
Line After

\newpage

\textbf{Keep the last two together}

\vspace{17\baselineskip}

\noindent Line Before
\begin{lstlisting}
First line
Middle lines
Middle lines
Middle lines
Last line
\end{lstlisting}
Line After

\end{document}

Answer 1

An unanswered question with my ol' listings. How nice.

Replace the incumbent vspace - depending how you look at it - on listings.sty with abovedisplayskip and belowdisplayskip respectively.

To sum it up, we are going to line 1723:

 \else
 \lst@ifdisplaystyle
    \lst@EveryDisplay
    \par\penalty-50\relax
    \vspace\lst@aboveskip

And modify it to:

\else
\lst@ifdisplaystyle
\lst@EveryDisplay
\par\penalty-50\relax
\lst@belowskip\lst@aboveskip

Then to line 1776 regardless of its historical context:

 \else
         \lst@ifdisplaystyle
             \par\penalty-50\vspace\lst@belowskip

and modify it as well:

 \else
         \lst@ifdisplaystyle
             \par\penalty-50\lst@aboveskip\lst@belowskip

Your sample:

 \documentclass{article}

 \usepackage[a6paper]{geometry}
 \usepackage{listings}

 \begin{document}

 \textbf{Keep the first two together}

 \vspace{15\baselineskip}

 \noindent Line Before
 \begin{lstlisting}
 First line
 Middle lines
 Middle lines
 Middle lines
 Last line
 \end{lstlisting}
 Line After

 \newpage

 \textbf{Keep the last two together}

 \vspace{15\baselineskip}

 \noindent Line Before
 \begin{lstlisting}
 First line
 Middle lines
 Middle lines
 Middle lines
 Last line
 \end{lstlisting}
 Line After

 \end{document}