Dear all,
I am computing the conditional variance decomposition, using the command conditional_variance_decomposition in stochsimul, Dynare version 4.2.1.
Does Dynare compute it at the mode or mean of the posterior distribution?

If you just estimated the mode of the posterior distribution, the variance decomposition is computed at the mode. If you run an MCMC the decomposition is done at the postrior mean (by default).