Increase Open Cursors

We have a customised integration process that uses RTI call to an AX class to pass xml and update data in a table. The xml is valid but the process is failing with the error

"The upper limit of open cursors for Microsoft Dynamics has been exceeded (250)."

I can see the limit set to 250 on the serer config. This is just a test run on a Test server and there is no option to perform kernel upgrade so I thought the quickest easiest way to get the test through was to increased the param to 500.

However i have done this on both AOSs used for integration and restarted the service and the re-test is still showing the error referring (250) as the limit.

How do i ensure the new limit takes effect?