# Auto linebreak using action in MSC

I am trying to draw a message sequence chart using LaTex. Currently I have some problems with a long action. How can I make it to linebreak automatically?

This is the part of the MSC (before asking, I have included the msc package and it compiles well)

\newcommand\setmscoptions{\setlength{\instdist}{5cm}\setlength{\levelheight}{1.5 \levelheight}\setlength{\instwidth}{3cm}}

\setmscoptions
\begin{msc}{Sequence Chart}
\declinst{A}{}{A}
\declinst{B}{}{B}
\declinst{C}{}{C}

\action*{This is a very log action that does not fit on one line}{B}
\end{msc}


Putting the text in a \parbox works fine here.

\documentclass{article}
\usepackage{msc}
\newcommand\setmscoptions{%
\setlength{\instdist}{1cm}% % reduced from 5cm
\setlength{\levelheight}{1.5 \levelheight}%
\setlength{\instwidth}{3cm}}

\begin{document}

\setmscoptions
\begin{msc}{Sequence Chart}
\declinst{A}{}{A}
\declinst{B}{}{B}
\declinst{C}{}{C}

\action*{\parbox{3cm}{This is a very long action that does not fit on one line}}{B}
\end{msc}
\end{document}