Space for 439 vehicles in practice, the reality is that it takes a mix of 2/3/4/5 car units so units isn't necessarily the right metric.
58 tracks (excluding head shunts, washer roads etc. which can't be used for stabling /maintenance) @ between 2 to 16 cars each.
That is the crux of the stabling capacity of any location that requires train formations to be shunted, reformed, maintained, washed, CET'd etc. There is no ONE specific answer to the original posters question, as stabling plans largely revolve around the train service applicable at any specific time, and the unit types involved (20 m or 23 m cars, or a mix of both), verses physical siding lengths.
And in the case of maintenance locations, as above, a percentage of usable siding space has to be kept free for shunting, reforming etc.
To give one example of a stabling/maintenance location, which was also the 'home' base of three/four stock types, so therefore also had to accommodate the 5% (or so) of each type that was not in traffic on any one day, had a total capacity of about 400 cars (20 m stock), taking
every siding into account. But from a planning/daily service point of view, the maximum numbers of cars permitted to be stabled after close of service each night was about 200.
This was one specific place, with which I was very familiar, and many other locations with the same sort of remit, will vary depending on local circumstances.
