Arbortext Command Language > set Command Options > set undolimit
  
set undolimit
set undolimit= n
This command specifies the maximum memory, in bytes, to use for undo buffer space for each open document. The default setting is 500 KB (or 512,000 bytes) of memory. The preference can be adjusted to a number of between 1 and 66536 to allow for more memory to be made available for the undo. If set to 0, there is no limit other than available virtual memory. Note that if you set this number too low, you will inhibit undo capabilities.  Setting the preference to an excessively high value could affect performance. 
The undo limit is based on volume of data deleted.  Arbortext Editor holds the deleted data in memory.
The undo buffer is allocated for each document. When a document is closed, its undo history will be discarded and the memory released.
* 
A change to this option does not take effect until the next document is opened. Setting this option to a low limit may prevent the undo command from restoring the last change.
Examples
set undolimit=50000
set undolimit=0