1. A computer implemented system for determining whether stack allocation is possible, the system comprising: an allocation unit configured to allocate a task object created by a method frame in a first thread to a stack in response to: calling a first instruction in the method frame and a second instruction in the method frame, wherein: the first instruction allows the task object to escape from the first thread to a second thread for parallel processing, the second instruction causes the first thread to complete the task object if the task object has not escaped from the first thread to the second thread, and the second instruction causes the first thread to wait for completion of the task object by the second thread if the task object has escaped from the first thread to the second thread, the task object does not escape from the second thread to a third thread during the parallel processing after the task object has escaped from the first thread to a second thread, and an instruction, other than the first instruction, that allows the task object to escape from the first thread is not called in the method frame.