AddUnitToStock limit

It appears that you can't add more than 11 units into a tavern via the AddUnitToStock native. I've tried to override the limit by calling SetAllUnitTypeSlots(12) to no avail. I am able to set a lower limit instead (for example 5).

For the reference blizzard.j 's InitNeutralBuildings calls:

where bj_MAX_STOCK_ITEM_SLOTS=11. It might be possible that that is the maximum value it can be set to.

So is the limit hard-coded to be 11? Is there any way to overcome this?

Well, you know that on the commandcardthere's only space for 12 buttons, so that's 11 stock units/items and one hero selection button.
So, even if you could technically add more units to the shop, they wouldn't show up on the commandcard.

Some maps avoid this by having it moving through several screens, each with 11 slots (removing and then adding periodically).

The 11 at any one time is almost certainly hardcoded though.

The hero selection button is not compulsory for the proper operation of a building that sells units added with AddUnitToStock anyway, but Blizzard might have had that in mind when they made Marketplaces and the add-to-stock natives :(.