Unlike the webcallserver startup script, the setenv.sh file is not overwritten on subsequent updates, therefore it is not necessary to restore this setting after every update.
Using service parameter while launching from non-root user (since build 5.2.801)
Since build 5.2.801, WCS is launching from 'flashphoner' user for better security. In this case, maximum opened files limit can be set using service parameters
sudo nano /etc/systemd/system/webcallserver.service
Maximum opened files limit is set with
LimitNOFILE parameter, for example
[Service] User=flashphoner Group=flashphoner LimitNOFILE=100000 ...