Performance considerations for connection and sign-on routines
Your sign-on exit routine is part of the critical path for transaction processing in IMS and CICS®. Therefore, try to execute as quickly as possible.
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Avoid
writing SVC calls like GETMAIN, FREEMAIN, and ATTACH. Also avoid I/O
operations to any data set or database. To improve performance, you
might be able to delete the list of groups that process in Section
3 of the sample sign-on exit routine.
The sample sign-on exit routine can issue the RACF® RACROUTE macro with the default option SMC=YES. If another product issues RACROUTE with SMC=NO, a deadlock might occur.
Your routine can also enhance
the performance of later authorization checking. Authorization for
dynamic SQL statements is checked first for the CURRENT SQLID, then
for the primary authorization ID, and then for the secondary authorization
IDs. If you know that a user's privilege most often comes from a secondary
authorization ID, then set the CURRENT SQLID to this secondary ID
within your exit routine.