Users and processes are provided with various features to control the memory usage by a cache and pool dynamically at runtime. The cache and pool can be initialized on demand to remove idle objects of classes from them without the server being restarted. When the cache and pool reach their maximum sizes, idle objects in them may be removed to make room for newly active objects using various strategies in batches, where the schedule (periodicity), size and processing time of each batch can be dynamically adjusted. When a newly created object is being added to a full cache where each object is enrolled in a transaction, one or more active objects may be passivated from the cache based on various criteria to make room for the new instance to be added. Various features of the cache and pool can be defined in a configuration file.