1. A computer program product for executing a prefetch data machine instruction, defined for a computer architecture, for performing a prefetch cache action on a cache, the computer program product comprising: a storage medium readable by a processing circuit and storing instructions for execution by the processing circuit of a processor for performing a method comprising: executing, by the processor, the prefetch data machine instruction, the execution comprising: determining, by the processor, whether the prefetch data machine instruction is configured to perform a data prefetch cache action or a cache line ownership operation, the data prefetch cache action for prefetching a cache line of data from memory to the cache, the cache line ownership operation for changing cache access ownership of a line of data in the cache; using a value of an immediate field of the prefetch data machine instruction to determine an address of an operand in memory; and performing, by the processor, the determined data prefetch cache action or a cache line ownership operation, on a cache line associated with the determined address.