What is libelli doing in Catullus 1

Question

In Catullus 1 we have:

Quare habe tibi quidquid hoc libelli,
qualecumque, quod, o patrona virgo,
plus uno maneat perenne saeclo.

I am not sure what libelli is doing.

Without it, I would put hoc in the subjunctive clause and translate as:

Hence, have for yourself, whatever, of whatever kind, so that, to the patrona virgo, this endures more than one generation.

Answer 1

Libelli is in the genitive of quantity, used after a noun of quantity to specify "of what." In addition to strict quantities like libra ("pound"), Latin uses this genitive with indefinite quantities, often "substantivized adjectives or pronouns in accusative or nominative," e.g. quid, multum, plus, nihil, etc.

A classic example of this construction is: "Quid novi?" = "What's new?" (lit.: "What of new?")

Here is an example from Cicero that uses quidquid:

quicquid malefici, sceleris, caedis erit, proprium id Rosciorum esse debebit. (Cic. Rosc. Am. 42, 122)

^{Whatever evildoing, crime, or violence there is, the Roscii surely will have a hand in it.}

Here's a translation broken up into parts:

Quare, habe tibi - "Therefore, please accept..."
quidquid hoc libelli - "...whatever book this is..."
qualecumque - "...as it is."