  Recent SPH simulations by Martin et al. (2014) suggest a circumstellar
gaseous disk may exhibit coherent eccentricity-inclination oscillations due to
the tidal forcing of an inclined binary companion, in a manner that resembles
Lidov-Kozai oscillations in hierarchical triple systems. We carry out linear
stability analysis for the eccentricity growth of circumstellar disks in
binaries, including the effects of gas pressure and viscosity and secular
(orbital-averaged) tidal force from the inclined companion. We find that the
growth of disk eccentricity depends on the dimensionless ratio ($S$) between
$c_{\rm s}^2$ (the disk sound speed squared) and the tidal torque acting on the
disk (per unit mass) from the companion. For $S\ll 1$, the standard Lidov-Kozai
result is recovered for a thin disk annulus: eccentricity excitation occurs
when the mutual inclination $I$ between the disk and binary lies between
$39^\circ$ and $141^\circ$. As $S$ increases, the inclination window for
eccentricity growth generally becomes narrower. For $S\gtrsim$ a few,
eccentricity growth is suppressed for all inclination angles. Surprisingly, we
find that for $S\sim 1$ and certain disk density/pressure profiles,
eccentricity excitation can occur even when $I$ is much less than $39^\circ$.
