Method, system and computer program product are provided for selectively separately updating multiple system time clocks or synchronously updating the multiple system time clocks (STCs). Separate or simultaneous updating of the system time clocks is attained by selectively adjusting the addresses to the system time clocks in updatable address register fields. A first address value is provided to a first address register associated with a first STC register and a second address value is provided to a second address register associated with a second STC register. Independent updating of the first STC register and the second STC register is performed when the first address value and the second address value are different, while synchronous updating is performed when the first address value and the second address value comprise a common address value. The technique can be extrapolated to any number of clocks to be updated.