A desirable characteristic of modern parallel applications is the ability to dynamically select the amount of resources to be used to meet requirements on performance or power consumption. In many cases, providing explicit guarantees on performance is of paramount importance. In streaming applications, this is related with the concept of elasticity, i.e. being able to allocate the proper amount of resources to match the current demand as closely as possible. Similarly, in other scenarios, it may be useful to limit the maximum power consumption of an application to do not exceed the available power budget. In this paper we propose Nornir, a customizable C++ framework for autonomic and power-aware parallel applications on shared memory multicore machines. Nornir can be used by autonomic strategy designers to implement new algorithms and by application users to enforce requirements on their applications.