Global files, local files, static, usropn - which is best in a service pgm

We've recently installed 7.1 (jumped over 6.1) and now I have choices. I've created a service program with two subprocedures, each accessing a different file. As was previously my custom, the F specs are global, before the subprocedures, with usropn specified. The subprocedure will be called from batch, interactive and probably a web stored procedure so I don't want a bunch of file opens and closes (could be 1,000s when called from batch) happening automatically. I usually check for %open in the subprocedure and have the calling pgm call one last time to close *all files. Before starting I read a nice article in July, 2013 IBM Systems Mag by Jon and Susan (Thx!) that explained new methods of global and local file definitions and controlling opening and closing files.

Now I'm confused. Are there real advantages to local files defined perhaps with static over global files with usropn controlling opens/closes? Or is just a preference?

TIA
Jack

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