This article describes the current support available for using Oracle Database 18c or 19c with Gen 8.6 generated applications and the Client Server Encyclopedia (CSE). It also covers internal support testing done for the Gen 8.5 Client Server Encyclopedia (CSE). 

Release: Gen 8.6
Component: Generated applications, Client Server Encyclopedia

Release: Gen 8.5
Component: Client Server Encyclopedia

Gen 8.6 Generated Applications

Oracle 18c:
Gen 8.6 Windows runtime PTF RTN86121/SS08664 (ORACLE 18C SUPPORT) provides the ability to rebuild Gen runtimes aecoran.dll and stuboran.exe for respective Windows C and GUI applications plus the Oracle DDL Loader tioraddl.exe. NOTE: This PTF has now been superseded by Gen 8.6 GA Complete (WKS86200/SO09618)

For Gen applications running under Unix/Linux no PTF is required and all that is needed is to relink the Gen DBMS shared library for Oracle (libae_oracle.*) using the ORACLE_HOME for 18c.  This is documented on the Gen 8.6 techdocs page: Gen™ 8.6 > Implementation Toolset > UNIX and Linux Implementation Toolset > Rebuilding DBMS Shared Libraries

Oracle 19c:
As of September 21, 2020, Oracle 19c is officially supported. No PTFs required for runtime.
See Community announcement: Certification Complete: Oracle 19c for Runtime and CSE

Gen 8.6 Client Server Encyclopedia (CSE)

** As of the September 21, 2020 announcement (Certification Complete: Oracle 19c for Runtime and CSE), the following information has also now been superseded by official support of Oracle 19c for Windows CSE in PTF CSN86204/SS14886, which itself has now been superseded by the 8.6.3 consolidation PTF WKS86300/LU06327 (Gen 8.6.3 Consolidation).  Note that there has never been any official support for the Windows CSE with Oracle 18c**

The Gen 8.6 Windows/Oracle CSE is 32-bit software and requires the 32-bit Oracle 12c (12.1.0.x or 12.2.0.x) client. The CSE runtime file csedb.dll is dependent on Oracle 32-bit client runtime file ORASQL12.DLL and therefore the Oracle client must stay at version 12c. However per "Client / Server Interoperability Support Matrix for Different Oracle Versions (Doc ID 207303.1)" an Oracle 12.1.0 or 12.2.0 client is compatible with an 18c and 19c server and thus the CSE database itself can in theory be at version Oracle 18c or 19c and still be compatible with the CSE server software running an Oracle 12c client i.e.

• #9 - 11.2.0.3 or 11.2.0.4 only. For Oracle Autonomous Transaction Processing and Oracle Autonomous Data Warehouse, there is additional limitation and 11.2.0.4 is the minimum supported client version.
  ...

• #12 - 12.1.0.2 only. For 11.2 interoperability, 11.2.0.4 is required.
  
  

The Gen support team have successfully conducted basic testing for the configuration and usage of a Gen 8.6 Windows CSE against an Oracle 18c (18.3) and Oracle 19c (19.3) database using the Oracle 12.2 32-bit client. For AIX Gen 8.6 CSE (32-bit software) & HP-UX Gen 8.6 CSE (64-bit software) it is also expected that there will be no problems using an Oracle 12c 32-bit/64-bit client with an Oracle 18c or 19c database.
NOTE: These test results do not represent an official certification.

Gen 8.5 Client Server Encyclopedia (CSE)

Along the same lines as the Gen 8.6 Windows/Oracle CSE, the Gen 8.5 Windows/Oracle CSE is 32-bit software and requires the 32-bit Oracle 11g (11.1.0.x and 11.2.0.x) client. The CSE runtime file csedb.dll is dependent on Oracle 32-bit client runtime file ORASQL11.DLL and therefore the Oracle client must stay at version 11g. However per the above "Client / Server Interoperability Support Matrix for Different Oracle Versions (Doc ID 207303.1)" an Oracle 11.2.0.3 or 11.2.0.4 client is compatible with an 18c or 19c server and so the CSE database itself can in theory be at version Oracle 18c or 19c and still be compatible with the CSE server software running an Oracle 11g client.
The Gen support team have successfully conducted basic testing for the configuration and usage of a Gen 8.5 Windows CSE against an Oracle 18c (18.3) and Oracle 19c (19.3) database using an Oracle 11.2 32-bit client. For AIX Gen 8.6 CSE (32-bit software) & HP-UX Gen 8.6 CSE (64-bit software) it is also expected that there will be no problems using Oracle 11g 64-bit client with Oracle 18c or 19c database. 
NOTE: These test results do not represent an official certification.
Also, Gen 8.5 reached End Of service i.e. end of support, on June 30, 2021 (CA Gen 8.5 End of Service Announcement)

Gen 8.6 Technical Requirements:
Gen™ 8.6 > Technical Requirements > Third-Party Software Version
Gen™ 8.6 > Technical Requirements > Development Platform Environments

Gen 8.5 Documentation (now pdf only): Gen™ 8.5