The libraries the pair frequent near the family's home at Oran Park, in Sydney's south-west, are an opportunity for Henry to gather armfuls of books on whatever topic tickles his fancy that week.

But Ms Gabbey said their "favourite outing" offered more than the books that lined the shelves.

"I think it's a really nice environment. It's a safe place we can go and hang out and I feel comfortable there, my son feels comfortable there. There are people of all different ages. We feel welcome."

It's an amenity the NSW Public Libraries Association and Local Government NSW will fight to preserve amid insufficient funding they say threatens the viability of 360 public libraries across the state.

They will urge both sides of politics to double spending and commit to a sustainable funding model for libraries in the lead-up to next year's state election through the Renew our Libraries campaign.

From Wednesday, public library users across NSW will be encouraged to sign a petition calling for a fairer funding model.

Local Government NSW president Linda Scott - who is also a City of Sydney councillor - said funding for public libraries had reached "crisis point" and they were struggling to maintain services.

She said the Berejiklian government slashed recurrent funding to libraries by 5 per cent in its most recent budget.

It also cut off "much-needed" infrastructure funding, which is still available in regional areas, for metropolitan libraries, Cr Scott said.

“This will result in cuts to library opening hours, fewer programs for parents and children and reduced book and digital collections."

Cr Scott said libraries played an increasingly important role in cities, where high-density housing meant public spaces were vital, and in regional areas, where drought had tightened household budgets.

"Libraries are changing from places that hold our books to community loungerooms," she said.

The NSW government's 7.8 per cent contribution to total funding is the lowest of any state, according to LGNSW, and well below Victoria at 18 per cent and Queensland at 12 per cent.

“The NSW government now contributes just $23.5 million a year to support more than 360 libraries across the state," Cr Scott said.

"This compares with a local government contribution of more than $314 million a year.”

Cr Scott said that placed "an unfair and unsustainable burden" on "already stretched" local governments to pick up much of the bill.

NSW Public Libraries Association president Dallas Tout - who is a Wagga City councillor - said public libraries boosted the state's economy.

"Each year NSW public libraries receive over 35 million visits. They support over 3000 full-time equivalent jobs and make a $330 million contribution to the NSW economy."

They also helped support the government’s childhood literacy and education goals, he said.

Arts Minister Don Harwin has previously said the Berejiklian government was committed to working with councils to enhance library services and facilities across the state.

Labor leader Luke Foley said, if elected, he would double library spending and set up a $25 million public library infrastructure fund for upgraded buildings and equipment.

Cr Scott said councils unanimously vowed to push for more state funding for public libraries, and to recognise their vital role in communities, at the Local Government NSW Conference in 2017.