SAP MaxDB X Server is only needed for network communication.
For local communication, that is, when the database and the database application (or database tool or the interface) are on the same computer, SAP MaxDB uses shared memory for communication. Two exceptions are the event dispatcher functions in Database Manager CLI and the JDBC interface, which require X Server even for local communication.
You are not using event dispatcher functions in Database Manager CLI or the JDBC interface.
Stop X Server using the following command:
x_server stop