hashcat keeps ending with "killed", what am I doing wrong?

All,

I'm wondering if you can offer some assistance.  I'm trying to test out hashcat and learn how to use the program.  When I run the following command it runs for about 3 minutes and ends in "killed".  What am I doing wrong?  The database is very large 2GB so I'm assuming perhaps this could be the issue?

root@kali:/usr/share/hashcat# ./hashcat.bin -m3200 -a0 /root/users.txt /usr/share/wordlists/rockyou.txt 

Initializing hashcat v0.49 with 1 threads and 32mb segment-size...

Killed