interpretation of part of assembly output

I'm looking at some assembly language output by icc -S (v16) and see lines like this:

     vmovups  %zmm0, 960(%rsp,%rdx)         #300.3 c7 stall 2

What is the "c7 stall 2" part telling me?

Is there a document somewhere that explains the more esoteric aspect of an assembly listing?