how to invoke maps library?

shiyiming

There is a libname maps in SAS librarys which is similar with sashelp, but I cannot use it directly like we can do 'proc print data=sashelp.class;run;' directly without assign libname sashelp.
The SAS log indicated libname map is not assigned.
so, just wonder someone can help: how can I complete 'libname maps 'SAS-data-library';'

proc gmap map=maps.us data=work.sites;
   id state;
   choro region/discrete;
run;
quit;

thanks a lot.