  Finite-temperature Drude weight (spin stiffness) D(T) is evaluated within the
anisotropic spin-1/2 Heisenberg model on a chain using the exact
diagonalization for small systems. It is shown that odd-side chains allow for
more reliable scaling and results, in particular, if one takes into account
corrections due to low-frequency finite-size anomalies. At high T and zero
magnetization D is shown to scale to zero approaching the isotropic point
{\Delta}=1. On the other hand, for {\Delta}>2 at all magnetizations D is nearly
exhausted with the overlap with the conserved energy current. Results for the T
variation D(T) are also presented.
