VMS Help FORTRAN, /DEBUG, PARAMETERS  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Controls how PARAMETER constant definitions are communicated to the
  debugger, subject to the setting of SYMBOLS.

  PARAMETERS=USED, the default, specifies that only those PARAMETER
  constants that are actually used in the program unit are made known
  to the debugger.

  PARAMETERS=ALL specifies that all PARAMETER constants are made
  known to the debugger.  If many PARAMETER constants are defined,
  this can greatly increase the size of the object module and
  executable image.