  We present results of numerical modeling made for the galactic stellar disk
embedded in the spherical halo. The non-linear dynamics of bending
instabilities developed in the disk is studied. The axisymmetrical bending mode
is considered as a main factor increasing the disk thickness. The model
dependence between the disk thickness and the halo to disk mass ratio $M_h/M_d$
is inferred. The modeling results enable us to estimate the dark halo mass for
several edge-on galaxies. The obtained values of $M_h/M_d$ for the galaxies
considered are of order 1 - 2.
