      SUBROUTINE ISTACK
 
C-----------------------------------------------------------------------
C  I(NITIALIZE) STACK
C
C  PREPARES STACK AND EXTERNAL DISK FILE
C  THIS SUBROUTINE IS CALLED FROM MAIN
C-----------------------------------------------------------------------
 
      IMPLICIT NONE
*KEEP,ETHMAP.
      COMMON /ETHMAP/  ECTMAP,ELEFT
      DOUBLE PRECISION ECTMAP,ELEFT
*KEEP,RUNPAR.
      COMMON /RUNPAR/  FIXHEI,THICK0,HILOECM,HILOELB,
     *                 STEPFC,NRRUN,NSHOW,PATAPE,MONIIN,
     *                 MONIOU,MDEBUG,NUCNUC,
     *                 CETAPE,
     *                 SHOWNO,ISHW,NOPART,NRECS,NBLKS,MAXPRT,NDEBDL,
     *                 N1STTR,MDBASE,
     *                 DEBDEL,DEBUG,FDECAY,FEGS,FIRSTI,FIXINC,FIXTAR,
     *                 FIX1I,FMUADD,FNKG,FPRINT,FDBASE
     *                ,GHEISH,GHESIG
      COMMON /RUNPAC/  DSN,HOST,USER
      DOUBLE PRECISION FIXHEI,THICK0,HILOECM,HILOELB
      REAL             STEPFC
      INTEGER          NRRUN,NSHOW,PATAPE,MONIIN,MONIOU,MDEBUG,NUCNUC,
     *                 SHOWNO,ISHW,NOPART,NRECS,NBLKS,MAXPRT,NDEBDL,
     *                 N1STTR,MDBASE
      INTEGER          CETAPE
      CHARACTER*79     DSN
      CHARACTER*20     HOST,USER
 
      LOGICAL          DEBDEL,DEBUG,FDECAY,FEGS,FIRSTI,FIXINC,FIXTAR,
     *                 FIX1I,FMUADD,FNKG,FPRINT,FDBASE
     *                ,GHEISH,GHESIG
*KEEP,STACKF.
      COMMON /STACKF/  STACK,STACKP,EXST,NSHIFT,NOUREC,ICOUNT,NTO,NFROM
      INTEGER          MAXSTK
      PARAMETER        (MAXSTK = 12*340*2)
      DOUBLE PRECISION STACK(MAXSTK)
      INTEGER          STACKP,EXST,NSHIFT,NOUREC,ICOUNT,NTO,NFROM
*KEND.
 
C-----------------------------------------------------------------------
 
      IF ( DEBUG ) WRITE(MDEBUG,*) 'ISTACK:'
 
      NTO    = 0
      NFROM  = 0
      NOUREC = 0
      NSHIFT = 0
      STACKP = 0
      ELEFT  = 0.D0
      ICOUNT = 1
      RETURN
      END
