zdsm.c repeatedly called to load/delete iggcsi00

[dkelosky]

zds.cpp invokes iggcsi00 multiple times for large lists of data sets which incurs the overheard of loading and deleting the module on each call. We should load the module once and delete once after the list operation is complete

[dkelosky]

chatting with @zFernand0 we can load and save (for reuse) services on first usage.