An application can have custom class loaders that load class files from locations that might not be part of the regular class path. In such situations dbx cannot locate the class files. The CLASSPATHX environment variable lets you specify to dbx a path for the class files that are loaded by their custom class loaders. For example, CLASSPATHX=.:/myloader/myclass:/mydir/mycustom causes dbx to look in the listed directories when it is trying to locate a class file.