Conditions for formation of planetary chaotic zones are considered (criteria by Wisdom (1980), Holman — Wiegert (1999), and Shevchenko (2015)). The “mass parameter μ — critical orbital period Tcr” diagram is constructed. Based on the Shevchenko criterion (2015), an explicit dependence Tcr(μ) is derived. It is shown that all known circumbinary planetary systems satisfy the Holman — Wiegert and Shevchenko criteria and, in the diagram, concentrate toward the borders of stability.