In the literature, often the capture cross sections for spherical heavy-ions are calculated by virtue of the characteristics of the s-wave barrier: its energy, radius, and stiffness. We evaluate these quantities systematically within the framework of the double-folding model. For the effective nucleon-nucleon forces, the M3Y Paris forces with zero-range exchange part are used. The strength of this part is modified to fit the barrier energy obtained with the density-dependent finite-range exchange part. For the nucleon density, two options are employed.