The listing environment is provided and is similar to figure and
table, although it is not a floating environment.  Includes support
for \caption, \label, \ref, and introduces \listoflistings,
\listingname, \listlistingname.  It produces a .lol file.  It does not
change \@makecaption (unless the option bigcaptions is used), so
packages that change the layout of \caption still work.