Her job description says Madeline Adams is a social worker. But lately she’s begun volunteering for tasks she never had before at the St. Louis marriage counseling agency where she works: planning events, ordering supplies, stocking shelves. She estimates she’s put in hundreds of hours of unpaid overtime work.

Adams isn’t gunning for a promotion. She just wants to keep her job.

Bosses around the country these days are discovering it’s not too much to ask for a little extra help around the office. Anything but.

More employees seem to be showing up early, forgoing vacation time, taking on extra projects — and doing it all with a smile (whether real or otherwise).

It’s hard to say just how widespread the phenomenon is. But Labor Department figures show workers have sharply boosted their productivity over the past year as layoffs mounted. Workers’ output-per-hour jumped 2.7 percent during 2008 — nearly double the increase during 2007 and triple the increase in 2006.

Not all that extra productivity has been voluntary. Some workers are simply forced to do more as co-workers leave, notes Steve Davis, an economist with the American Enterprise Institute.

The pressure mounted Friday, when the government said employers cut 345,000 jobs in May, and the nation’s jobless rate hit a quarter-century high of 9.4 percent. Fear of being the next layoff is pushing some workers to fight harder to cling to their jobs, said Bruce Tulgan, founder of New Haven, Conn.-based Rainmaker Thinking Inc., workplace consultants.

Often, the efforts amount to common sense. People dress better and show up early. They say nice — OK, flattering — things to the boss. And they try to look busy.

“I’ve started to see a sea change,” Tulgan said. “A growing number of people are saying: ‘I’ve got to roll my sleeves up and do something now.’ They’re finding ways they can identify problems before they happen.”

Some workers are aiming for the “halo effect,” said Bernie Sparks, founder of the 21st Century Leadership workplace consulting: When managers decide who goes and who stays, those seen as having a halo over their heads stand a better chance of surviving.

That’s what Chris Kirkman is thinking. A graphic designer in San Diego, Kirkman plans to scrap the weeklong summer vacation he and his wife usually take. They’ll instead take off a Friday and go on a long weekend road trip.

Kirkman says he thinks avoiding absences can help an employee build a reputation as especially dedicated to the company.

“It kind of pays to hold on to your vacation days,” Kirkman said. “It not only helps when you get laid off, but it helps you work a little bit harder for your management to see.”

Tulgan says forgoing vacation time isn’t likely to save anyone’s job. Managers tend to calculate the overall value each worker brings, regardless of how much or how little vacation they take.

“But on the other hand, if you disappear on a long vacation and nobody really misses you, then you might be putting ideas in a manager’s head,” he said.

And it’s hardly guaranteed that anyone’s sudden boost in productivity — or attitude — can avert a layoff. Bosses tend to see through behavior that amounts to, well, sucking up, said Gary Walstrom, founder of Culture Index Inc. consulting firm in Kansas City, Mo.