Produce the prism map. The ID statement specifies the variable in the map data set and the response data set that defines map areas. The CDEFAULT= option sets the color of map areas that have missing data. The RELZERO option makes the prism heights relative to zero.

proc gmap data=sashelp.demographics(where=(cont=94))
          map=maps.africa density=low all;
   id id;
   prism pop / cdefault=yellow relzero;
run;
quit;