The PSOCC uses the following cookies during its operation.
PSOCC_Id and sqlAuthCookie - When you log in to the system, you are issued with this cookie (which uses it to store your identity) your web browser presents it every time you load a new page. PSOCC checks the cookie against a register of logged in users so that it knows what account you logged into the system with.
SpryMedia_DataTables_[...] - Remembers your chosen filters and sort orders on various tables of records you see around the site (for example, the list of service users).
Selected-Tab-[...] - Remembers which tab you had selected the last time you visited a particular page. This allows the same tab to be open when you return to the page later.