1. A computer implemented method comprises: determining a usage level of a memory for a plurality of running applications, each running application being associated with a priority indicating a rank among the running applications, the usage level indicating an amount of the memory already in use; selecting a memory reduction operation associated with one or more APIs (Application Programming Interface) for a particular one of the running applications based on the usage level and a particular priority associated with the particular application; and notifying the particular application to perform the memory reduction operation to reduce the usage level and increase available space of the memory via the one or more APIs.