Chapter 8. System considerations 165
You can automate this process by putting all the previous steps in the same job, but you need
to schedule the job at a time when there are no other subsystems using the RECON. You
must also ensure that the discarded RECON is released by all the sharing online systems.
With only one online subsystem and no other users (batch jobs or utilities), you can perform
the /DIS OLDS command by executing an automated operator BMP. With multiple systems
sharing the RECON, you must propagate the command to the other systems. You can set up
the automatic RECON loss notification feature for this purpose.
8.3 SMF and RMF considerations
For SMF, you should check the SMFPRMxx member of SYS1.PARMLIB. A parameter called
DDCONS should be specified, and it should be set to DDCONS(NO). The default, if not
specified, is YES. Setting this to NO does not affect any ability to gather data. Specifying YES or
allowing DDCONS to default causes the system to consolidate DD information at every
interval, which is also specified in this parmlib member. This can be a CPU intensive task for
address spaces with a lot of open data sets, such as IMS and DB2, and can cause delays on
a cyclical basis.
The RMF VSTOR parameter can also cause cyclical delays when the detail option is chosen
for address spaces with large amounts of storage, such as IMS. The detail option can be
turned on and off by command if you want this information, but you should not leave it on
permanently or specify detail in the RMF start parameters.
8.4 Security considerations
IMS uses the SAF interface to check security. The product performing the security check can
be RACF or another security product. IMS does not support Security Maintenance utility
(SMU) after IMS Version 9. For this reason, security functions that required the use of SMU
can now be performed using RACF, RAS, and security exits.
Table 8-1 provides the various resource classes that need to be managed by RACF. If the
resource class does not exist in RACF, it needs to be defined by your RACF administrator.
Resource classes are defined in IMS using the RCLASS= keyword in the SECURITY macro
during IMS system generation. For a detailed description of the implementation of these
various options, consult the IMS Version 9: Administration Guide: System, SC18-7807.
In conjunction with the resource classes, there are startup and system generation parameters
that need to be considered. Most of these parameters can be changed in the DFSPBxxx
startup member in IMS. Some parameters can also be changed using IMS commands. The
IMS Version 9: Administration Guide: System, SC18-7807, provides a list of these
Table 8-1 Resource classes used by RACF
Description Class Name DB/DC, DCCTL, or DBCTL
Application group name AIMS DB/DC, DBCTL, and DCCTL
Command resource class CIMS DB/DC and DCCTL
Command group resource

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