documentclass{article}
usepackage{caption}
usepackage{listings}

DeclareCaptionFormat{fmt}{parbox{linewidth}{#1#2#3}}
captionsetup{,textfont=it,justification=raggedright,format=fmt,position=bottom}
lstset{frame=single}

begin{document}

begin{lstlisting}[caption={Hello World!}]
int a = 1;
int b = 2;
end{lstlisting}

begin{description}
item[A]
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
begin{lstlisting}[caption={Hello World!}]
int a = 1;
int b = 2;
end{lstlisting}
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
begin{lstlisting}[caption={Hello World!},captionpos=b]
int a = 1;
int b = 2;
end{lstlisting}
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
item[B]
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
end{description}

end{document}