A system and a method of scheduling a plurality of threads from a multi-threaded program. A shared arena is provided in user memory, wherein the shared arena includes a register save area for each of the plurality of threads. A processor, when allocated to the application, executes the application's user-level scheduler and selects a user-level thread from a plurality of available threads, wherein the step of selecting includes the step of reading register context associated with the selected thread from one of the plurality of register save areas. In multikernel systems, kernels having access to an application's register save areas can execute preempted threads from that application with no kernel-to-kernel communication. Likewise, kernels having access to an application's user-level run queues can execute ready-to-run threads from that application with no kernel-to-kernel communication.