A cache system, having cache sets, a connection to a line identifying an execution type, a connection to a line identifying a status of speculative execution, and a logic circuit that can: allocate a first subset of cache sets when the execution type is a first type indicating non-speculative execution, allocate a second subset when the execution type changes from the first type to a second type indicating speculative execution, and reserve a cache set when the execution type is the second type. When the execution type changes from the second to the first type and the status of speculative execution indicates that a result of speculative execution is to be accepted, the logic circuit can reconfigure the second subset when the execution type is the first type; and allocate the at least one cache set when the execution type changes from the first to the second type.