1. A computer-readable storage medium comprising instructions which, when executed, cause a machine to: create a shared loader accessible by a plurality of runtime systems in a shared memory, the shared loader to have a runtime representation of a class loaded in the shared memory to allow the class to be used by the plurality of runtime systems, wherein access to the shared loader by the plurality of runtime systems is restricted to receive a set of parameters providing a declarative description of the shared class loader via a declarative interface; and return a reference to the shared class loader, the declarative interface to further prevent each of the plurality of runtime systems from using their own shared loader or from specifying an application code to be used in the shared loader, and guarantee the class is loaded consistently in each of the plurality of runtime systems; and invoke the shared loader to load executable code to be shared by the runtime systems, the executable code to include a shared portion and a local portion wherein the shared portion of the executable code is stored in the shared memory, and the local portion of the executable code is stored in a local memory of a runtime system invoking the shared load.