The CONVERT CATALOG utility is indicated to be run on upgrade installs. It is not required in all situations.
If you do not have the CA IDMS SQL option installed, and do not have IDMS Visual DBA installed, then your CATSYS segment is probably still defined as NONSQL. As such, no CONVERT CATALOG should be run. The CONVERT CATALOG is only necessary for shops using either the SQL option or Visual DBA. To determine whether the utility is required, you can issue the following in OCF or BCF:
CONNECT TO SYSTEM; DISPLAY SEGMENT CATSYS;
If the segment is defined FOR NONSQL, then neither the SQL option nor VISUAL DBA is being used against this catalog, so the CONVERT CATALOG is not required.
It occasionally occurs that a shop is using IDMS SQL (or Visual DBA) and has defined their SQL application catalogs correctly, but their SYSTEM catalog is still defined as FOR NONSQL. This is not acceptable. If either the SQL option or Visual DBA is in use, then all catalogs (system and application) should be defined as FOR SQL. In each catalog segment, areas DDLCAT and DDLCATLOD should include the clause "STAMP BY AREA", and area DDLCATX should include the clause "STAMP BY TABLE".
If it is required, the CONVERT CATALOG should be run against every catalog defined in the DMCL. It is cumulative, and will apply all necessary catalog changes for any releases since the previous install.