USER-DPD: SSA with Kokkos: make stencil's sx, sy, sz variables public

  int *nstencil_multi;             // # bins in each type-based multi stencil

  int **stencil_multi;             // list of bin offsets in each stencil

  double **distsq_multi;           // sq distances to bins in each stencil

  int sx,sy,sz;                    // extent of stencil in each dim

  double cutoff_custom;            // cutoff set by requestor

  int xyzflag;                     // 1 if stencilxyz is allocated

  int maxstencil;                  // max size of stencil

  int maxstencil_multi;            // max sizes of stencils

  int sx,sy,sz;                    // extent of stencil in each dim

  int dimension;