CLEAR is clearing too much

I am probably missing something simple.
I checked the archives but did not uncover much.
The following is code snipped from a production program.
The line to clear the array W  also clears some elements
in array SLS.
Debug the program and display SLS, I saw some elements in
SLS were 0 after the CLEAR of W.
This is on V4R5, any suggestions.

Frank Kolmann


H OPTIMIZE(*NONE) OPTION(*NODEBUGIO)  ALWNULL(*USRCTL)
H DFTACTGRP(*YES)
D #F1             DS
D  W                             7S 0 DIM(18)
D #F2             DS
D  SLS                           7S 0 DIM(36)
C     *ENTRY        PLIST
C                   PARM                    #F1
C                   PARM                    #F2
C                   SetON                                        LR
C                   Clear                   SLS
C                   Z-Add     22            SLS
C                   Clear                   W