No. A phone stand is not necessary to use JIBB. As long as you have a steady surface to prop your phone against, JIBB will work. If you don’t have a phone stand, you can consider propping your phone against a stack of books, coffee mug, or household item (a roll of duck tape actually works great to sit your phone in).
Here are a collection of photos of some various way to position your phone to use JIBB with, or without a stand.