1. A processing block comprising: a storage sub-block; an execution sub-block to execute instructions; and a thread management sub-block coupled to the storage and execution sub-blocks, and equipped to store and maintain a thread switching structure in the storage sub-block to facilitate interleaving execution of a plurality of threads of instructions by the execution sub-block, with the thread structure including a current thread identifier identifying one of the plurality of threads as a current thread being currently executed by the execution sub-block, and a thread array of thread entries, one per thread, correspondingly describing the plurality of threads, each thread entry being created and added to the thread array by the thread management sub-block as part of the execution of a create thread instruction of a thread to spawn execution of another thread.