Refer to Figure 8 to see a detailed explanation of the RPG IV initialization subroutine.
The initialization subroutine allows you to process calculation specifications before 1P output. A specific subroutine that is to be run at program initialization time can be defined by specifying *INZSR in factor 1 of the subroutine's BEGSR operation. Only one subroutine can be defined as an initialization subroutine. It is called at the end of the program initialization step of the program cycle (that is, after data structures and subfields are initialized, external indicators and user data fields are retrieved, global files are opened, data area data structures, arrays, and tables are loaded, and PARM result fields moved to factor 1 for *ENTRY PLIST). *INZSR may not be specified as a file/program error/exception subroutine.
If a program ends with LR off, the initialization subroutine does not automatically run during the next invocation of that program because the subroutine is part of the initialization step of the program. However, if the initialization subroutine does not complete before an exit is made from the program with LR off, the initialization subroutine will be re-run at the next invocation of that program.
The initialization subroutine is like any other subroutine in the program, other than being called at program initialization time. It may be called using the EXSR or CASxx operations, and it may call other subroutines or other programs. Any operation that is valid in a subroutine is valid in the initialization subroutine, with the exception of the RESET operation. This is because the value used to reset a variable is not defined until after the initialization subroutine is run.
Any changes made to a variable during the initialization subroutine affect the value that the variable is set to on a subsequent RESET operation. Default values can be defined for fields in record formats by, for example, setting them in the initialization subroutine and then using RESET against the record format whenever the default values are to be used. The initialization subroutine can also retrieve information such as the current time for 1P output.
There is no *INZSR associated with subprocedures. If a subprocedure is the first procedure called in a module, the *INZSR of the main procedure will not be run, although other initialization of global data will be done. The *INZSR of the main procedure will be run when the main procedure is called.