If I remember rightly, S1's narration gives the mass ("humans and aliens wrapped in two million five hundred thousand tons of spinning metal, all alone in the night") and S2's gives the length ("a self-contained world five miles long, located in neutral territory"). S3's concentrates more on the plot than the setting, and S4's and S5's are collections of snippets and don't really have time to mention such details.

(With mass and length mentioned, one feels time ought to have turned up as well. I suppose "The year is 2258+n" for 0 ≤ n ≤ 4 might count, but that's not a dimension of the station. Perhaps Sleeping in Light ought to have had a modified narration :-)