LockTabel Funtion

Hi

Can anyone explain me how to use the LOCKTABLE function?

As an example, I can explain you my problem.

I am writing a code in which I need to locate all records in Customer table and need to block the customers whom balances are greater than credit limits. So before executing this code I need to lock the entire customer table in which case no one will be able to update customer master records.

I would be greatfull, if someone could explain me the consequences on this and the way I can make use of Locktable function.

Thank you!