1. A method of operating a processor, the method comprising: in response to a load-and-flag instruction that specifies a load source as an operand, acquiring ownership of a set of addressable storage locations, the acquired set covering the load source; in response to a first conditional-store instruction that specifies a first store target as an operand, storing a first result to the first store target if the previously acquired set remains owned and contents thereof remain unmodified; and in response to a successive second conditional-store instruction that specifies a second store target as an operand, storing a second result to the second store target if the previously acquired set remains owned and contents thereof remain unmodified.