  We show that a CP-violating phase can be model-independently determined from
the time-independent measurement of coherent B^0_s\bar{B}^0_s decays into
(D^{(*)\pm}_s K^{(*)\mp})(D^{(*)\pm}_s K^{(*)\mp}) states at the \Upsilon (5S)
resonance. This phase amounts to (-\gamma) within the standard model, where
\gamma is the well-known angle of the quark mixing unitarity triangle. It is
also possible to determine or constrain the B^0_s-\bar{B}^0_s mixing parameter
y_s from the same measurement.
