The advent of many-core architectures poses new challenges to the MPI programming model which has been designed for distributed memory message passing. It is now clear that MPI will have to evolve in order to exploit shared-memory parallelism, either by collaborating with other programming models (MPI+X) or by introducing new shared-memory approaches. This paper considers extensions to C and C++ to make it possible for MPI Processes to run into threads. More generally, a thread-local storage (TLS) library is developed to simplify the collocation of arbitrary tasks and services in a shared-memory context called a task-container. The paper discusses how such containers simplify model and service mixing at the OS process level, eventually easing the collocation of arbitrary tasks with MPI processes in a runtime agnostic fashion, opening alternatives to runtime stacking.