Autostart with Systemd service
First, execute the following command to create a directory for storing Systemd service file of individual users.
#mkdir -p ~/.config/systemd/user/
Then create xscreensaver.service file with nano text editor.
#nano ~/.config/systemd/user/xscreensaver.service
Put the following text into the fie.
#[Unit]
Description=XScreenSaver
[Service]
ExecStart=/usr/bin/xscreensaver -nosplash
[Install]
WantedBy=default.target
XScreenSaver will be automatically started at boot time.
#systemctl --user enable xscreensaver