  We consider microwave hyperfine transitions in the ground state of cesium and
rubidium atoms which are presently used as the primary and the secondary
frequency standards. The atoms are confined in an optical lattice generated by
a circularly polarized laser field. We demonstrate that applying an external
magnetic field with appropriately chosen direction may cancel dynamic Stark
frequency shift making the frequency of the clock transition insensitive to the
strengths of both the laser and the magnetic fields. This can be attained for
practically any laser frequency which is sufficiently distant from a resonance.
