Apple Inc is in very active discussions at the board level about what to do with its steadily growing hoard of cash and securities, Chief Executive Tim Cook said on Tuesday, responding to calls for the world's most valuable electronics company to put its massive cash reserves to work.

Cook, in one of his rare appearances before investors, also talked about a jaw-dropping opportunity in smartphones. He also said the iPad tablet trajectory was off the charts, adding that he foresaw tablets surpassing the personal computer market in unit sales eventually - eroding Microsoft Corp's Windows dominance.

He acknowledged an intense competitor in Amazon.com Inc and its Kindle Fire tablet, recognizing the online retailer has different strengths. Apple's shares rose to close at $509.46 on the Nasdaq, setting a record high on hopes of strong iPhone 4S demand and investor optimism over the potential launch of a new iPad in 2012.

Wall Street's other concern is the likelihood of Apple returning some of its $98 billion warchest to shareholders through dividends or share buybacks - even if it is only a one-time deal.

On Tuesday, the CEO urged investors at a Goldman Sachs technology conference to be patient about the cash reserves.

I only ask for a little bit of patience, so we do this deliberately and in the best interest of shareholders, Cook said.

He joked that Apple will not be holding any toga parties with the money.

It is not new that we are discussing it. It is being discussed more and in more detail.

Addressing another issue that persistently crops up on public forums, Cook stressed that the iPhone and iPad maker takes labor conditions in its globe-spanning supply chain seriously, addressing persistent criticism that its production partners may be mistreating workers.

Cook, who took over from Silicon Valley icon Steve Jobs after his October death, said his company had a very granular-level understanding of its partners' treatment of workers.

Apple said on Monday the U.S. non-profit labor group Fair Labor Association has begun an unprecedented inspection of working conditions at its main contract manufacturers, including Foxconn's plants in southern China, as the maker of the iPhone continues to grapple with persistent image problems there.

(Reporting By Poornima Gupta; editing by Richard Chang and Andre Grenon)

(Corrects cash to $98 billion, not $98 million)

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