IMS Version 8 Implementation Guide A Technical Overview of the New Features

Chapter 18. Automatic RECON loss notification 269

򐂰 This CHANGE command is not supported for /RMCHANGE usage, it only may be invoked

with DBRC command utility execution.

򐂰 This CHANGE command cannot be used if any DBRC instance using this RECON is

active, except for any DBRC instance which was started before ARLN was activated.

򐂰 Any subsequent commands in the DBRC command utility (DSPURX00) job step will fail.

򐂰 We recommend restricting access to this command to authorized personnel.

18.3 DSPSCIX0 details

Since the exit routine could be used with DBRC instances using different RECONs, the exit

routine should be able to handle different RECONs, maybe all of your RECON sets. Our

sample exit routine can be easily modified to do this. There is a table (in PLEXTABL DSECT)

in which you can create table entries for each set of RECONs. Some sample entries will give

you an example. For those sets using ARLN, the entries should include the IMSplex name

and an indicator that RC=00 will be returned. You should override any passed IMSplex

execution parameter as well.

You can code entries, including an indicator for a RC=04, to be returned for other sets of

RECONs not intended for use with ARLN. As mentioned in previous items, this allows the

RECONs to be accessed without SCI registration of the DBRC instance.

Using SMP/E for your own common version of this exit routine, you can provide a USERMOD

to apply to all of your zones and install it into the associated SDFSRESL libraries to be

implemented in all of your environments. Please refer to Example 18-8 on page 274.

The IMS provided default exit

If there is no DBRC SCI exit provided, IMS behaves as if the IBM supplied default exit were

used. You will find a sample DSPSCIX0 exit in the ADFSSMPL distribution library. Please

take a few minutes to review this exit. Our supplied default exit routine works as described

below:

򐂰 If IMSPLEX= parameter is specified:

– Returns the specified IMSplex name with RC=00

򐂰 If IMSPLEX= parameter is not specified:

– Uses lookup table to match the passed RECON data set name with an entry containing

the corresponding IMSplex name (the table is empty as supplied, you need to modify it)

– Returns IMSplex name from the table entry with RC=00

򐂰 If IMSPLEX= parameter is not specified and no match found in the table:

– Sets RC=04, meaning no SCI registration will be done. No IMSplex name will be saved

in the RECON and RECON access fails if the RECON contains an IMSplex name. If

the RECONs contain an IMSplex name, RECON access is denied.

The SCI is a prerequisite for automatic RECON loss notification.That means ARLN is only

available for IMS Version 8 systems running in an IMSplex environment. All IMS Version 6

and IMS Version 7 systems using DBRC are allowed to share the RECONs even though they

are not able to register with SCI and they cannot support ARLN.

Note: The DSPSCIX0 exit must be in an authorized library. If the library is concatenated,

only the data set containing the exit needs to be authorized. DBRC performs a specific

check on the dataset the module is loaded from to determine that it is contained in the

Authorized Program Facility (APF) list.