Common-envelope ejectability in binaries with massive giant donor stars and BH companions. For each evolutionary track of a massive giant with M_ZAMS between 10 and 80 M_⊙, we compute what would be the outcome of a CE phase initiated by that star at any given point during its post-MS evolution in a circular binary with a BH companion with mass M_BH = M_donor/q_crit (see text for detailed assumptions). The resulting ratio of the size of the remnant core of the CE donor R_remnant and the size of its Roche lobe R_{RL; post-CE} is color-coded in the figure as a function of M_ZAMS and the radius of the giant at the onset of the CE phase. Radii above the white diamonds (crosses) indicate giants that are past the onset (end) of core-helium burning in their evolution. The hatched region marks the parameter space where the giant donor has an outer convective envelope with f_conv = M_conv/M_env ≥ 0.1. The dotted region marks the parameter space where the CE ejection is possible (i.e., R_remnant/R_{RL; post-CE} <  1.0).