The following steps describe how to change the 'Number of messages deleted to reclaim the History List message space' value via Command Manager:
ALTER SERVER CONFIGURATION AUTODELETEMESSAGECOUNT <number_of_messages>
The target value should be entered in the <number_of_messages> field.
For details on the Message Replacement Policy in Strategy 9.x please refer to KB31333: New feature in MicroStrategy 9.x - Find and Replace Privileges