What role does "municipatum" play in this sentence?

Question

The abbot Berno of Reichenau, in the opening sentence of his Prologus in Tonarium, some time between 1021 and 1036, called himself the following:

licet parvus meritis, servus tamen Dei Genitricis Virginis municipatum in arce divinae speculationis

though small in merit, still a servant of the Virgin Mother of God citizenship(?) in the ark of divine speculation

I am puzzled how municipatum fits into the rest of the phrase. I figure it is not an adjective here, for it doesn't agree grammatically with servus. Could it perhaps be an accusative object to servus, as in "the one serving the citizenship of the Virgin Mother of God"? But then why servus and not, say, servans?

Sources: Gerbert Migne

Answer 1

Ah, I had been thinking erroneously of the second declension. But, if municipatus is a noun here, not an adjective, then naturally it would be declined to the fourth declension, whose genitive plural ending -uum was oft elided as -um in Medieval Latin.

I suppose the sentence might then be translated something like this:

servus tamen Dei Genitricis Virginis municipatuum in arce divinae speculationis

still a servant to the dwellings of the Virgin Mother of God in the fortress of divine speculation.

By which I suppose he is referring to the monastic communities.