Why split the file with awk if you are then going to process the data in memory anyway? Read and process the original file, perhaps writing the parts to new files along the way if they are needed for some other purpose.

See readdir for the Perl tool used to scan directory contents.

There's not much help we can give in reply to "I want to store data in a hash" because it simply doesn't tell us enough about why you want to do that nor what you want to store, nor how you want to access it.