UPDATE 1-Los Angeles officials brace for Jackson memorial

* Demand for tickets crashes server

* Los Angeles to Jackson fans: Stay home

* Memorial service, cost shrouded in mystery (Updates throughout with quotes, police staffing)

By Bob Tourtellotte

LOS ANGELES, July 3 (Reuters) - Los Angeles city officials are planning a massive security operation for Michael Jackson's public memorial service next week, and on Friday urged fans who do not win a ticket in a random drawing to stay away from the basketball arena where the singer will be memorialized.

Organizers have set aside a total of 17,500 tickets through an Internet-based lottery for the televised service at the Staples Center, and for a closed-circuit screening at the nearby Nokia Theater.

Within minutes of the system being announced at a news conference, the computer system crashed. Officials warned additional disruptions were likely as fans from around the world applied for tickets.

"You might want to consider watching this from the comfort of your own home," said Los Angeles City Councilwoman Jan Perry, who is doubling as the city's acting mayor.

A wide area around the venues in downtown Los Angeles will be blocked off for the 10 a.m. (1700 GMT) event. Both local and state law-enforcement agencies have been marshaled for duty.