In Berne Convention countries, anything you publish is automatically under your own copyright, unless you've agreed to terms to the contrary. (And publication on the Internet does count as publication.)

For example, when working under a contract, this often assigns the code you write during work hours to your employer. Your country's laws may even make that assumption by default, in the absence of specific copyright clauses in your contract.

PerlMonks, unusually for site of its nature does not have a terms of service document that users need to agree to. Such documents usually include language to the effect that users retain copyright on their contributions, but by posting material, they automatically give the website permission to publish them.

So, unless I've missed something subtle, yes, you own the copyright on code you publish on PerlMonks. (Unless your employer does!)

For a year or so, I've had a note on my home node clarifying the copyright and license for code I publish here.

The usual IANAL disclaimers apply.