7z may get killed due to low CPU or RAM capability of a server, because LZMA needs a lot of RAM for high level compression. Downgrading the compression level is a solution.
Here is an example:
7za a -t7z -mx0 -v100m -p -mhe foo.7z foo
The -mx0 means it does not even compress it, but just packs it. The number range is from 0 to 9. 0 means no compression, and 9 means the highest compression.
Why do we need a compression program like 7z without compressing anything? The reason is very simple. Your data can be sent or shared easier and safer. If you have a lot of files and a cheap Linux VPS you have to send a lot of links to your friends. If you pack it into one 7z file, only one link is needed. If you want multiple parts, you can add -v100m to it. You may not have enough money to buy a ssl certificate, and your friends do not know how to use scp or rsync, or you do not want to create guest users for your friends. In these cases, you need the -p -mhe options. They mean you can encrypt your files and the file list. 7z is the only free and open source solution to encrypt a file list currently.
Have fun; be free.