How to calibrate shocks' sd in dynare


I have very simple quesion.
That is how to calibrate shocks’ standard deviations in dynare.

Generally, parameters are calibrated, when their values are given before model block and are not written in estimated param block.
However, shocks’ standard deviaitons are not written in this way, as far as I know.

Thanks in advance.

That is what the

shocks; end;
block is for.