I\'ve been trying to create PL/SQL packages and running procedures on a local installation of Oracle 11gR2 on my computer, and I kept getting ORA-00900 error. Based on this
I've followed the advice in the comments and learnt that my problem isn't with my Oracle database installation at all.
I was using DBeaver while attempting to run some pl/sql script, and for some reason I don't know it failed with the ORA-00900. After posting the question I ran the same script in Toad for Oracle, and it works without any problem. Running the same script in SQL Plus also works okay.
I don't know what causes the error in DBeaver yet, but at least now I know the error code ORA-00900 does not mean my database is missing any Procedural Option function. In hindsight I probably should have tested my script in SQL Plus first before posting the question.
Anyway, thanks for the comments guys, it really helped me tons.
DBeaver cannot execute PL/SQL as they view it as Oracle specific, which it is. This may be implemented some time in the future.