10. MODIFICATION › 10.2 User Exits

10.2 User Exits

Before implementing an exit, determine whether the required
modification can be accomplished by means of parameter
modification or file tailoring.

At times, additional system customization is needed to tailor
CA MICS to your data center. There are many user exit points
provided within CA MICS. Each of these points corresponds to
a position in the CA MICS logic where user modification:

   o  is likely to occur, based on our experience

   o  presents only a slight possibility of compromising the
      CA MICS database or operational integrity

   o  is relatively easy to document and understand

Using the CA MICS exit facilities to augment CA MICS
processing logic is the safest method of system modification.
Generally, you have four methods with which to augment,
change, and enhance CA MICS.

   o  CA MICS standard option and parameter definitions

      The diverse installation and definition options provide
      most users with adequate provisions for customizing
      CA MICS.

   o  Modification through user exits

      Often there may be site-dependent requirements that are
      not adequately addressed through the standard options
      and parameters.  In these cases, one or more of the
      user exits provided with CA MICS may be used to insert
      user-written routines that satisfy the requirements.

   o  Extension through user-written components

      Although most users do not initially consider this a
      way of modifying a standard CA MICS product, the
      development of user-written components may be the most
      advantageous method.  For example, often it may be
      better to write a user component to handle additional
      SMF data than to attempt to modify the logic of the
      CA MICS CICS Analyzer.

  o   System code modification

      Finally, if all else fails, you may be able to satisfy
      your site's requirements by implementing a source code
      change.


GENERAL EXIT CONSIDERATIONS

You should carefully explore whether or not it is necessary
to develop a user exit routine.  To this end, first ensure
that the requirement cannot be satisfied through one of the
standard options or definitions.  For assistance, contact
Technical Support at http://ca.com/support.

The design, coding, testing, and implementation of CA MICS
user exit routines should be done carefully, since errors may
result and corrupt the data.  You should be meticulous in the
definition and validation of the exit routines to ensure that
system integrity and performance is not adversely affected.

If an exit must be used, refer to Chapter 9 of this guide for
a description of the location of the exit in the DAILY
update.  For a better understanding of CA MICS user exits,
see Section 4.3 of the SMG, User Exit Facilities.

Product exits are classified according to their purpose.
They include product input, output, parameter-related, and
accounting exits.  Input exits are invoked as the raw input
records are read.  Output exits are invoked just before
CA MICS writes an observation to the CA MICS database.

The CICS Analyzer provides the input exit   _USRSEL.  You can
use this exit to select or exclude input data that meets
special site-defined criteria, add data elements, or modify
record fields as they are read.

One output exit routine is provided for each product file.
You can use this output exit routine to selectively block the
writing of specified records, alter data elements in the
records, or produce additional records for the target file or
a user-defined file.

The product parameter-related exits are also user exits, but
they are defined as part of the standard CA MICS installation
process.  They are normally associated with other parameters
or options.  For example, the Account Code Derivation Routine
is a user exit routine for completing values for account
codes that were defined in the separate but related CICACRT
member of prefix.MICS.PARMS.  CICACRT is the Account Code
Definition parameter member.  These exits are identified in
this chapter, but are described in Chapter 7 of this guide.

The user exits for the CICS Analyzer are discussed in detail
in the following sections:

    1 - Input Exits
    2 - Parameter-Related Exits
    3 - Output Exits