The nation's civilian unemployment rate rose slightly to 6 percent last month, but an unusually large increase in the number of people at work and other labor figures indicated the U.S. economy was still expanding strongly in October, the Labor Department reported yesterday.

The unemployment rate had dipped to 5.9 percent in September, its lowest level since November of 1979. The department said the increase last month was not statistically significant, and that the rate has been essentially at 6 percent since June.

Actual payroll figures showed a 549,000 increase in the number of jobs, with 108,000 coming in goods-producing industries, including a 63,000 gain in manufacturing. Factory overtime jumped from 3.6 to 4 hours a week, the highest level in 14 years, the department said.

Even before the recent plunge in the stock market, a number of economists had been predicting slower economic growth in coming quarters as a result of smaller gains in consumer spending, personal income and employment growth. While consumer spending growth may remain weak, analysts said the big employment gains suggest the economy was still expanding at a healthy clip prior to the stock market tumble on Oct. 19. The data on which yesterday's labor report was based was collected in the week prior to what is now known as Black Monday.

"The labor market continued strong in October," Janet L. Norwood, commissioner of labor statistics, told Congress' Joint Economic Committee. "Large gains in employment occurred in both the household and business surveys. The labor force also expanded considerably, leaving unemployment essentially unchanged." Norwood termed the factory job picture "an especially bright spot." For the second month in a row, she said, about 60 percent of industries added workers, with especially large gains in fabricated metal products, machinery and electrical equipment.

In three industries -- furniture; rubber and plastics, and printing and publishing -- employment reached record levels, she added.

But the biggest gains continued to come in service-producing industries, as they have during most of the current expansion. According to the department's payroll survey, jobs in service industries of all types reached almost 78 million last month, compared with 25 million in goods-producing industries, out of which 19.2 million were in manufacturing.

The civilian labor force grew by 500,000 in October, to 122.1 million, while civilian employment rose by 415,000, according to the department's monthly household survey.

The number of people seeking work but unable to find it increased by 85,000, to 7.2 million. Another 5.4 million had part-time jobs while wanting to work full time, an increase of about 175,000 from September.

The unemployment rate for adult men rose from 5 percent in September to 5.1 percent last month. The rate for adult women fell from 5.4 percent to 5.2 percent. That for teen-agers rose to 17.4 percent from 16.3 percent.

The unemployment rate for blacks fell from 12.3 percent to 12 percent, and was down from 14.3 percent in October 1986. However, the black rate was still more than twice as high as that for whites, which rose last month from 5.1 percent to 5.2 percent. A year earlier it was 6 percent.

In the past year, 3 million additional jobs have been created, divided about equally between men and women. About 100,000 of the new jobs went to teen-agers.

As the labor markets have gotten tighter in the past year, the number of people out of work for extended periods of time has come down somewhat. Of the 7.2 million unemployed people, 13.5 percent -- about 960,000 -- had been without a job for more than half a year, down from 14.9 percent a year earlier.

Meanwhile, the share of people who had been unemployed for five weeks or less rose from 41.9 percent to 45.4 percent. This sort of shift is characteristic of a strongly growing job market as individuals more readily leave jobs, confident that they can find another one.

Despite a generally tighter labor market, wage gains continued to be moderate last month, the department said. Its hourly earnings index, which is adjusted for changes in overtime and job shifts among industries, increased only 0.1 percent. The index increased 2.6 percent in the past 12 months.

In her testimony, Norwood noted that hourly compensation increases had been "more moderate than usual" during the current economic expansion, and that in manufacturing, at least, productivity increases have been large enough that unit labor costs have gone down, helping to moderate inflation.