Allow debugging by dbx without object (.o) files.
With -xs, all debug information is copied into the executable file. If you move executables to another directory, then you can use dbx and ignore the object (.o) files. Use this option when you cannot retain the .o files.
Without -xs, if you move the executables, you must move both the source files and the object (.o) files, or set the path with either the dbx pathmap or use command.