[Socjopapa]

powinien mieć na nie pokrycie w gotówce i/lub kredytach, które udzielił.

No właśnie. Ty takiego numeru nie możesz odwalić, tj. nie możesz pożyczyć nigdy więcej niż faktycznie posiadasz. Jak masz 100 j.p. możesz pożyczyć 100 j.p. Bank takich ograniczeń nie ma.

A Hans pisze o czymś innym niż ja mam na myśli, tylko nie potrafię przypomnieć sobie polskiej nazwy: z angielska to jest capital adequacy.

Na wiki opisali słowno-muzycznie to co ja napisałem na uproszczonym przykładzie:

When a commercial bank loan is extended, new commercial bank money is created if the loan proceeds are issued in the form of an increase in a customer's demand deposit account (that is, an increase in the bank's demand deposit liability owed to the customer). As a loan is paid back through reductions in the demand deposit liabilities the bank owes to a customer, that commercial bank money disappears from existence. Because loans are continually being issued in a normally functioning economy, the amount of broad money in the economy remains relatively stable. Because of this money creation process by the commercial banks, the money supply of a country is usually a multiple larger than the money issued by the central bank; that multiple was traditionally determined by the reserve requirements and now essentially by other financial ratios (primarily the capital adequacy ratio that limits the overall credit creation of a bank) set by the relevant banking regulators in the jurisdiction.