For example, adding the line MaximumMemoryForSubsetUndo=20480 to the configuration file instructs the server to allot 20480 kilobytes (20 MB) of memory for the Undo/Redo stack.
Parameter type: optional, dynamic
Generally, larger subsets require greater amounts of memory to store a usable Undo/Redo stack. If you find that the Cognos® TM1® server is not storing a sufficient number of Undo/Redo steps for your subsets, increase the value of MaximumMemoryForSubsetUndo.
If this parameter is not explicitly set in the Tm1s.cfg file, the maximum amount of memory dedicated to the Undo/Redo feature of the Subset Editor is 10240 kilobytes (10 MB).