Cash held by a bank as fiduciary may be deposited to the credit of the bank as such fiduciary on time or demand account with itself or with any other bank the deposits of which are insured by the federal deposit insurance corporation. Unless otherwise provided by the writing creating the trust, if such funds are deposited with itself the bank shall secure such deposits with securities described in section 6-352, subsection D, paragraph 2, or other security approved by the deputy director for the purpose, in the amount of the deposit, subject to section 6-245, subsection C.