  The quantum Heisenberg antiferromagnet on the stacked triangular lattice with
the intralayer nearest-neighbor exchange interaction J and interlayer exchange
J' is considered within the non-linear $\sigma$-model with the use of the
renormalization group (RG) approach. For J' << J the asymptotic formula for the
Neel temperature $T_{Neel}$ and sublattice magnetization are obtained. RG turns
out to be insufficient to describe experimental data since it does not take
into account the $\mathcal{Z}_2$-vortices. Therefore $T_{Neel}$ is estimated
using the Monte-Carlo result for the 2D correlation length [10] which has a
Kosterlitz-type behavior near the temperature $T_{KT}$ where the vortices are
activated.
