On Linux, there is a global and per-user limit of open file descriptors (read: maximum number of open files). The global limit is distribution and kernel specific, the per-user limit is set to 1024 by default. However, some applications, like Lotus Domino, Oracle, ... require to have more than 1024 open files.
The current global limit can be checked with:
To change the global limit, you can do:
echo 65536 > /proc/sys/fs/file-max
Unfortunately, if you set the limit with the above command, it will not be saved after a reboot. To change this parameter at every boot, you have to add this to /etc/sysctl.conf:
fs.file-max = 65536