Max size of AMQ (Active MQ) data folder is 5 GB and it can be verified in file ..SOI\tomcat\webapps\activemq-web\WEB-INF\caifwmq.xml as below
storeUsage storeUsage limit="5gb" name="AMQStore"/ /storeUsage
The way it works is, connector logs data in AMQ in flat files, this data is processed by SOI manager and removed from flat files. If you are sure if your connectors will not log data which exceed more than 1 GB then you can reduce size.
But in some cases if data logged by connectors exceed more than 1 GB then it will become single point of failure and SOI manager will stop processing alerts.
My recommendations is not to change any settings here because if your connector is not logging more data to AMQ flat files then it will never exceed 1 GB and will not eat space on disk.
In order to save storage, is it safe to minimize storeUsage limit to 1 GB?