The maximum population size of a pyGlobOpt run determines the pool size for structures that are available to be randomly chosen for the onlooker and employed bees. Onlooker and employed bees require four and three structures respectively to perform their operations (c.f. equations 3 and 4). The pool is filled with the lowest energy structures up to the defined maximum population size. In practice, this is a way to modify the diversity of structures available to the onlooker and employed bees.