Don,
I advise against any "one size fits all" or "blanket" recommendations such as changing ALL of your binding directory entries to specify "*DEFER" ... and then re-binding all of your applications programs and service programs.
There is some (minimal) amount of extra overhead when using *DEFER -- because a small "dynamic loader stub" is bound into each program in place of the dynamic linkage to each "target" service program. At runtime, when the application calls any of the procedures or functions (entry points) in this "stub" -- the "stub" code invokes the APIs needed to dynamically load the actual "target" *SRVPGM needed, and then updates all of the procedure pointers in an internal storage table so that any subsequent calls will route directly to the target service program routines, and the stub then transfers control to the desired procedure that caused this stub to be invoked in the first place.
Applying *DEFER "everywhere" in a large application with many *SRVPGMs may not be "a good idea" for the following reasons:
#1. Consider the impact of "testing" such as massive change. The "test" team would need to re-test the ENTIRE application suite, after making such a massive change to the code base.
#2. how will your team deploy and install such a massive change, especially if you have the applications running on multiple "live" production systems or LPARs, or if you distribute software to one or more customer or client sites?
NOTE: do not attempt to change the way the IBM-supplied runtime routines are bound.
"BEST PRACTICES" -- USE CASES:
In my opinion, *DEFER is best used only for certain situations, such as for "error handling" routines that are only used when certain error situations arise; that way, applications do not need to incur the overhead of loading those "error handling" *SRVPGMs and initializing their static storage, etc., for the majority of cases where those error situations never occur or do not arise.
I hope that helps.
All the best,
Mark S. Waterbury
On Thursday, August 26, 2021, 01:54:30 AM EDT, Don Brown via RPG400-L <rpg400-l@xxxxxxxxxxxxxxxxxx> wrote:
I have just had a look at our binding directories and all are *IMMED
Many were created long ago and I think new service programs have been
added just copying.
I also notice when doing a dspsrvpgm <service_program> that the IBM
service programs are also *IMMED
Example
Service
Program Library Activation
QRNXIE QSYS *IMMED
QRNXIO QSYS *IMMED
QRNXUTIL QSYS *IMMED
So from what I have read I should have no concern in changing our
application binding directory entries to *DEFER and recreating our service
programs ?
Is that correct ?
Thanks
Don
midrange.com
