  A sensitivity of twist-4 and $\alpha_s$ values extracted in the NLO QCD
analysis of nonsinglet SLAC-BCDMS-NMC deep inelastic scattering data to the
choice of QCD renormalization scale (RS) is analysed. It is obtained that the
high twist (HT) contribution to structure function $F_2$, is retuned with the
change of RS. This retuning depends on the choice of starting QCD evolution
point $Q_0$ and x. At $Q_0 > 10 GeV^2$ the HT contribution to $F_2$ is retuned
at small $x$ and almost not retuned at large $x$; at small $Q_0$ it exhibits
approximate RS stability for all x in question. The HT contribution to $F_ L$
is RS stable for all $Q_0$ and x. The RS sensitivity of $\alpha_s$ also depends
on the choice of $Q_0$: at large $Q_0$ this sensitivity is weaker, than at
small one. For $Q_0^2=9 GeV^2$ the value
$\alpha_s(M_Z)=0.1183\pm0.0021(stat+syst)\pm0.0013(RS)$ is obtained. Connection
with the higher order QCD corrections is discussed.
