1. A method comprising: operating real-time middleware associated with at least one node of a data distribution system to communicate data samples with middleware on the same or on other nodes, where each node is a separate computer, the middleware of the nodes operating using a publish-subscribe communication model to provide a publish-subscribe interface for distributing data samples among a plurality of user applications, each user application executing in a separate address space on the same or on other nodes, but having access to a global data space to publish and subscribe the data samples, wherein the data samples in the global data space are accessible to each user application via the middleware of the node, the method further comprising, by the real-time middleware associated with one of the at least one node of the data distribution system: allocating, to the middleware associated with that one node, at least one pool of a plurality of fixed block size units of memory of the node; based on loan requests for dynamic memory elements on behalf of a user application executing on that one node for storing published or subscribed data samples, providing an indication to the user application of at least one of the allocated fixed block size units to be lent on behalf of the user application; and maintaining a list of which allocated fixed block size units are being lent from the pool on behalf of the user application on that one node, including maintaining the list based on return requests relative to fixed block size units of the at least one pool for stored published or subscribed data samples for which a borrowing application is finished using the lent fixed block size units of the at least one pool; wherein the allocating step is executed previous to the loan requests; and substantially all of the dynamic memory elements of the real-time middleware associated with that one node are provided from the at least one pool of allocated fixed block size units based on the loan requests from the user application on that one node for storing published or subscribed data samples.