Local definitions use automatic storage. Automatic storage is storage that exists only for the duration of the call to the procedure. Variables in automatic storage do not save their values across calls.
Global definitions, on the other hand, use static storage. Static storage is storage that has a constant location in memory for all calls of a program or procedure. It keeps its value across calls.
Specify the STATIC keyword to indicate that a local field definition use static storage, in which case it will keep its value on each call to the procedure. If the keyword STATIC is specified, the item will be initialized at module initialization time.
In a cycle module, static storage for global definitions is subject to the RPG cycle, and so the value changes on the next call to the cycle-main procedure if LR was on at the end of the last call. However, local static variables will not get reinitialized because of LR in the cycle-main procedure.
Using automatic storage reduces the amount of storage that is required at run time by the program. The storage is reduced largely because automatic storage is only allocated while the procedure is running. On the other hand, all static storage associated with the program is allocated when the program starts, even if no procedure using the static storage is ever called.