FAA you can log anytime you are the sole manipulator of the controls as PIC. Technically if the a/p is on and you are p/f you cant log pic but i did it anyway since the cant check of the a/p was on or not
JAA, you can't log PIC if you are f/o.
You can log PICUS as said but only if the company has a aproved PICUS program, and then only op to 150 hours. The PICUS program is for getting the 150 Hrs PIC required for the ATPL and since a lot of pilots with the integrated pilot program that go straight to a "ATPL" airplane dont have sufficent PIC hours to reiceive an ATPL. But remember writing PICUS is more than beeing P/F you have to be acting as commander under supervision, You also need to take all commander desicions. So part of the PICUS program is a command training , and usually done with copilots opgrading to commander. (at least here with us).
The value of hours picus is to be debated with a new job anyway. any comapany will understand that somebody with "to many" PICUS hours was flying as an F/O anyway
If you wanna keep track of your P/F hours just make a collum in your logbook with P/F
and remember if you are logging PICUS let the PIC sign your logbook.
Good luck,
SOAB