Actually in reality banks are never reserved constrained, that is, they can always make loans if they have credit worthy customers, loans create deposits. In the world we live in (not the economics textbook fairyland) banks need a certain amount of reserves in order to ensure smooth settlement of the plethora of draws on, and deposits into and out of a certain bank on any given day. They need depositors and lenders to ensure capital adequacy, not so they can lend it out in fractional reserve, money multiplier mumbo jumbo. The RBA's role in this is they provide a window (discount window) for which if banks are short of reserves they can access (unlimited, they create the currency after all) money at whatever rate, banks avoid this because the rate is typically higher then their other funding costs.
Basal 3 guidelines state that banks need to have a minimum 30 days liquid coverage ratio of tranche 1 assets, namely, government bonds or cash. As the Australian bond market is miniscule compared to the amount that would be needed under the requirements, the suggested solution is to allow the RBA to offer a 'special facility' whereby banks can be guaranteed by the RBA for the amount that would otherwise have to be held as cash/bonds. If anyone still doubts the RBA has unlimited AUD's then they should consider this point..
