  The complete fusion of $^6$Li with $^{28}$Si and $^{64}$Ni nuclei, ranging
from subbarrier energies up to values well above the Coulomb barrier, is
studied using the continuum discretized coupled channels method. We investigate
the sensitivity of the results to the largest energy used in the discretization
of the continuum, including closed channels. Our results reveal that, as long
as the states in the continuum are not limited to too small energies, the
specific upper bound adopted is not relevant as the complete fusion
cross-section is fairly insensitive to it above a threshold. Convergence with
respect to this parameter is rapidly reached, so that closed channels play a
role only at low collision energies. A good agreement with the available
experimental data is obtained.
