1. A computer system comprising: at least one processor; a hierarchy of storage including a cache, wherein locations represented in the hierarchy are addressable by the processor; and a conditional multi-store mechanism that acquires ownership of a first cache line covering the target of a load-and-flag operation, wherein as long as the first cache line remains owned and contents thereof remain unmodified, the conditional multi-store mechanism allows results of plural successively executed conditional-store operations to become visible, individually and successively, in the storage.