  Critical parameters defining the local nucleation field in amorphous
ferromagnetic microwires with positive magnetostriction are obtained
analytically through scaling procedures. Exact value of the nucleation field is
obtained numerically as a function of geometric parameters of anisotropy
distribution, which is fully taken into account instead of being averaged out.
It is established that the value of nucleation field depends predominantly on
the steepness of anisotropy change withing the boundary between axial and
radial domains, while the maximal value of anisotropy inside the wire or an
overall average is not relevant.
