Center Latex lstlisting

Instead of using linewidth you should consider to use xleftmargin and xrightmargin (cf. texdoc listings, Chapter 4.10). The following code works without any center or minipage environment:

\lstset{
  caption=Descriptive Caption Text, 
  basicstyle=\footnotesize, frame=tb,
  xleftmargin=.2\textwidth, xrightmargin=.2\textwidth
}
\begin{lstlisting}
    printf("this should be centered!");
\end{lstlisting}