The alls-construction is part of the dialects of Midwestern American English. It refers to the appearance of -s on the word all. It is also sometimes spelled with an apostrophe before the -s.
There has been some discussion on linguistlist.org about the possibility that the -s may be a reduced form or is or as. Some have also pointed out other potentially related cases where an -s suffix appears in spoken English, such as Hows about we leave soon? or That's a long ways away from here.
As for the use of alls, the -s suffix characteristic of the alls-construction has a restricted distribution, and cannot always appear on all. For example, -s would not appear on phrases such as all or nothing. The -s also cannot appear on all in inverted sentences (sentences in which the verb precedes the subject) or ordinary (or free) relative clauses (clauses starting with who, that, which, whose, where, and when). Some speakers of the dialects of which alls is characteristic of also reportedly do not allow the alls-construction with second person subjects.
The sentence you provided is not one of the characteristic uses of alls as it has been described. It seems to resemble phrases like all the more enjoyable. It is possible that it is a genuine construction/colloquialism for some speakers, but if so, it hasn’t been described in the linguistics literature, as far as we know.
Here’s a page we’ve written on the alls construction: https://ygdp.yale.edu/phenomena/alls-construction