Can a company post the job roles (which don't have openings at the moment but will have in the future) over its careers page? If yes, what are pros and cons of it?

We want to post the job roles we have in the organization over website and redirect all our applicants (who sends mails) to the careers page on the website. But none of the job roles have openings at the moment. We might have openings in the coming months.
In this scenario, is it ok to post such roles over website and mention clearly that we will revert in the future when we have openings. So that when we have a requirement , we will have a pool of applications ready to process.
But I am doubtful if the companies does like this or not. Let me know the pros and cons of doing it.

Dear friend,
Nothing to wrong to collect the database of the candidates even there no vacancies for the few posts. However, while asking the applicant's to apply on your company's website, you need to be cautious. You can create a recruitment page, and ask the applicants to upload their CV. For the categorisation purposes, you may create a dropdown menu also.
If you ask the CVs for the roles where there are no vacancies then it may create the confusion in the minds of the employees who are performing that role. They might think that the company is looking for their replacement or view receiving a CV as a threat to their job. Please avoid such misunderstanding.
Thanks,
Dinesh Divekar