OvrSetRetry procedure

  DECLARATION:  OvrSetRetry(Size : LongInt)

      PURPOSE:  Sets the size of the probation area in the overlay buffer

         UNIT:  Overlay

      REMARKS:  Any free space in the overlay buffer is considered to be
                part of the probation area.  If an overlay falls within the
                Size bytes the tail of the overlay buffer, it is put on
                probation.  The default size of the probation area is 0.
                A value of 0 effectively disables the probation/reprieval
                mechanism.

                There is no clearly defined formula for determining the
                optimal size of the probation area.  The best results can
                usually be achieved using values from 1/3 to 1/2 of the
                overlay buffer size.