The source view displays source line numbers by default at debugger
  startup.  To hide (or display) line numbers at debugger startup:

  1.  While using the debugger, choose Show Line Numbers from the File
      menu on the main window.  Line numbers are displayed when a
      filled-in button appears next to that menu item, and vice versa.

  2.  Choose Save Options from the Options menu on the main or optional
      view window.  This creates a new version of the debugger resource
      file with the new settings.

  When you later start the debugger, line numbers are either displayed or
  hidden accordingly.

  You can also set the startup default for line numbers by setting the
  following resource to either True or False in the VMSDEBUG.DAT resource
  file.

  DebugSource.StartupShowSourceLineno