A system and method are provided for improved handling of data in a cache memory system (105) for caching data transferred between a processor (110) capable of executing a program and a main-memory (115). The cache memory system (105) has at least one cache (135) with several cache-lines (160) capable of caching data therein. In the method, a cache address space is provided for each cache (135) and special instructions are generated and inserted into the program to directly control caching of data in at least one ofthe cache-lines (160). Special instructions received in the cache memory system (105) are then executed to cache the data. The special instructions can be generated by a compiler during compiling of the program. Where the cache memory system (105) includes a set-associative-cache having a number of sets each with several cache-lines (160), the method can further include the step of determining which cache-line in a set to flush to main-memory (115) before caching new data to the set.