Openssl - Initialization vector cannot be used?

I am encrypting something in my server (using php). 

The encryption is done with aes-256-cbc as method, a password and an initialization vector , which is generated by my php script. 

The problem is there is no option as far as I can see in the opennssl decrypt function, for using an initialization vector… 
Even in this openssl plugin tutorial iv is not used…

Is it not possible?

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