API GetMerchantItemMaxStack

Gets the maximum stack size for an item from the active merchant. maxStack = GetMerchantItemMaxStack(index)

Arguments

 * index : Number - The index of the item in the merchant's inventory.

Returns

 * maxStack : Number - The maximum stack size for the item.

Note
This does not seem to work properly as of patch 2.3, and always returns 1 for items that sell in stacks (such as arrows). Try GetItemInfo instead.