End of File handling in Cache and IRIS

In Cache End of file throws error but in IRIS no indication of End of file. I have to do an explicit $ZOF. How are you handling/detecting End of File in IRIS?

In cache this line will throw End of file error -  F PREC=1:1 U FILE R REC  D SOMETHING

But in IRIS this goes to forever, has anyone noticed this behaviour in IRIS?