In my catalog, core.99586 files is creating

.Core files are created when the php script or program in memory is incorrectly closed or interrupted. Then the core. files are created containing a dropping of memory which can be used to diagnose a malfunctioning application.

Often core files. they are also created due to incorrect directives in local php.ini .user.ini or htaccess files

Core files. which take up space on the server can be deleted, however the fact that they are creating indicates that something with the scripts is not working properly and should be reviewed before deleting them in order to diagnose the cause of the application malfunctioning.