SPL1104: "%s:E(L%d), Unexpected text on LHS of SET statement."
The target of the SET statement, i.e., the LHS of the SET statement in the indicated line must contain only local variables, and/or INOUT/OUT parameters.
The LHS of a SET statement cannot be a Reserved Word or a System variable. So check whether the LHS for these and change if they are one. The LHS can be a valid identifier. The LHS cannot be any undefined variable.