Defining the IMS catalog without DBRC

The IMS catalog, unlike other HALDBs, can be defined without using DBRC.

The IMS catalog is a PHIDAM database. As a type of HALDB, PHIDAM databases cannot normally be used without enabling DBRC to manage the database partitions. However, the IMS catalog can be configured to run without using DBRC. This is called the unregistered catalog scenario because the partition definitions are not registered in the DBRC RECON data sets.

Recommendation: Use DBRC to manage the IMS catalog database partitions. Unregistered catalog databases are supported by some but not all HALDB utilities, and other restrictions apply. See Using HALDB utilities with an unregistered IMS catalog.

Procedure

Create a new DFSMDA member of the IMS.PROCLIB data set to dynamically allocate the catalog partition definition data set.
Modify the following JCL for your environment:
```
//DALOC    JOB
//*
//STEP    EXEC IMSDALOC
//SYSIN     DD  *
   DFSMDA TYPE=INITIAL
   DFSMDA TYPE=CATDBDEF,DSNAME=dsn
   DFSMDA TYPE=FINAL
   END
/*
```
The dsn value is the name of the new partition definition data set. See the DFSMDA macro topic for an explanation of each parameter.
Create the catalog database with the Catalog Partition Definition Data Set utility (DFS3UCD0).
The catalog partition definition data set is populated with the values specified with the HALDB and PART parameters of the utility.
```
//S1       EXEC PGM=DFS3UCD0,REGION=0M                
//STEPLIB  DD  DSN=IMS.SDFSRESL,DISP=SHR
//DFSRESLB  DD  DSN=IMS.SDFSRESL,DISP=SHR  
//DFSHDBSC  DD  DSN=...,DISP= 
//SYSPRINT DD  SYSOUT=*                   
//IMS      DD  DSN=IMS.DBDLIB,DISP=SHR 
//SYSIN    DD  *                         
HALDB=(NAME=DFSCD000)                
PART=(NAME=DFSCD000,PART=xxxxxxxx,                     
      DSNPREFX=xxxxxxxx,                     
      KEYSTCHAR=xxxxxxxx)   
/*                                      
```
The name DFSCD000 in the HALDB and PART statements contains the default catalog prefix DFSC. If your catalog uses an alias name prefix, substitute it in the JCL.

The root key for a catalog record is the value of the RHDRSEQ field in the HEADER segment of the catalog record. This key value is generated by the IMS catalog populate utility (DFS3PU00) or the ACB generation and catalog populate utility (DFS3UACB). The value is created by concatenating the record type and the IMS member name of the resource. The record type is eight characters long and is right-padded with blank characters. The IMS member name is always eight characters long.

For example, the root key for a DBD record with the name ACF12000 is the following:
```
DBD     ACF12000
```
The root key for a PSB record with the name MXG88888 is the following:
```
PSB     MXG88888
```
The root key value is also used to sort catalog records into database partitions, if your catalog database consists of more than one partition. The partition high key for the last partition in the database must be high enough to contain the highest-key record in the catalog.

The catalog secondary index can have only one partition.

Identify the unregistered catalog database to IMS with the UNREGCATLG parameter in the DATABASE section of the DFSDFxxx member of the IMS.PROCLIB data set.

Modify the following sample section for your environment:

/******************************************************************/
/* Database Section                                               */
/******************************************************************/
<SECTION=DATABASE>
UNREGCATLG=(DFSCD000,DFSCX000)     /* Unregistered IMS catalog DB */
/******************************************************************/
/*                                                                */
/******************************************************************/