Do you mean cirrostratus clouds? Plain old stratus clouds are low altitude and composed of water - they are not an ice crystal hazard. Cirrostratus do contain ice crystals but these are a) Much bigger (by about one order of magnitude) and b) Much less dense (by about 2 orders of magnitude). This means they are nowhere near as big a hazard in terms of ICI than the very dense ice clouds we see being produced near Cbs.
Same with normal cirrus clouds, by the way: They're about an order of magnitude less dense than the Cb associated clouds and (as far as I know) have not been implicated in any rollback events.