Patent ID: 7574569

Claim:
In a control environment, a method for managing at least one store of memory items from the control environment, the method comprising: setting a free-space size threshold for the store; setting an age parameter for the store, the age parameter specifying a duration; comparing an amount of free space in the store with the free-space size threshold; if the amount of free space in the store is less than the free-space size threshold, then selecting and removing memory items from the store and marking as free the space previously occupied by the removed memory items until the amount of free space in the store is greater than or equal to the free-space size threshold; comparing an age of a memory item in the store with the duration specified by the age parameter; and if the memory item is older than the duration specified by the age parameter, then removing the memory item from the store; wherein the memory items comprise history blocks comprising data from the control environment.