Openings for the month actually decreased slightly, falling 25,000 to 7.45 million. However, workers that the Bureau of Labor Statistics classifies as unemployed declined by 387,000 to 5.82 million, leaving the gap at 1.63 million.

On the openings front, the gap between vacancies and available workers continued to be huge.

Hirings increased to 5.9 million for the month, a gain of 240,000 from March, the Job Openings and Labor Turnover Survey indicated. The hiring rate rose to 3.9%, an increase of one-tenth of a percentage point. The total hirings was the most recorded in the data series' history going back to December 2000.

The total number of workers hired rose to a new high in April, according to Labor Department data released Monday. But despite this, the amount of available jobs still vastly outnumbers unemployed workers.

"In sum, the labor market remains strong and poised for continued solid job growth," Ward McCarthy, chief financial U.S. economist at Jefferies, said in a note. "Despite the 21.4 [million] private sector jobs that have been generated to-date this cycle, the private business sector continues to generate a very strong demand for labor that is evidenced by the very large number of job openings that business wants to fill. The biggest threat to job growth is available supply, not demand for labor."

Separations increased by 70,000 to 5.58 million, a rate of 3.7%, which was unchanged from March.

The JOLTS data lags other employment indicators by a month but is nonetheless watched closely by the White House and the Federal Reserve as an indicator of labor market slack. A large number of available workers compared with job openings would indicate a tight market in which wages should be rising.

The more widely watched nonfarm payrolls report measures the amount of workers hired compared with the jobs lost.

The quits level also rose for the month, up 21,000 to 3.48 million for a rate of 2.3%, which was unchanged on the month and up one-tenth from a year ago. The reading is considered a good gauge of worker confidence as people feel comfortable leaving their current positions for better opportunities.

At an industry level, professional and business services hired 1.23 million new workers. Trade, transportation and utilities led openings with 1.47 million.

Nonfarm payrolls on net increased by 224,000 for April, the month covered in the JOLTS survey, before easing to a 75,000 gain in May.