Option
/M[[AP]]
The /MAP option adds to the map file all public (global) symbols defined in object files. When /MAP is specified, the map file contains a list of all the symbols sorted by name and a list of all the symbols sorted by address. If you do not use this option, the map file contains only a list of segments. If you also want to add line numbers to the map file, use the /LINE option.
The /MAP option causes a map file to be created even if you did not explicitly tell the linker to do so. By default, the map file is given the same base name as the executable file with the extension .MAP. You can override the default name by specifying a new map filename in the mapfile field or in response to the List File prompt.
Under some circumstances, adding symbols slows the linking process. If this is a problem, do not use /MAP.