What is the bank's requirement to have money in customers accounts in order to lock ASBA payment option?

The money will be required by the bank to place the bid for IPO shares via ASBA payment option. SEBI clearly stated that banks won't accept IPO applications before blocking the bidding amount (for ASBA).

The amount will be locked until the registrar / Stock exchange request bank releases the funds. This could happen if the investor hasn't received the allotment or IPO application was rejected.