UL/DB2

Introduction

The User Language/DATABASE 2 Interface (UL/DB2) provides a multithreaded connection from a Model 204 User Language procedure to a DB2 database to retrieve DB2 data or manipulate DB2 tables.

For Model 204 version 7.5 and later, UL/DB2 is installed using the JAUSQLJ job stream. See installing the UL/DB2 interface for details.

The UL/DB2 topics provide information for these users:

User	Responsible for...
Model 204 system managers	Making a Model 204 environment ready to support the interface, and defining and controlling security. System managers should know how to set up Model 204 Online and BATCH204 environments.
DB2 database administrators	Granting PLAN and table privileges. DB2 database administrators should know how to precompile and bind a PLAN, and grant access to a PLAN.
Application programmers	Developing User Language procedures that use embedded SQL statements. Application programmers should know User Language and SQL syntax.

Overview

The User Language/DATABASE 2 Interface (UL/DB2) allows a Model 204 User Language procedure to use embedded SQL statements to access a DB2 database. User Language becomes, in effect, a host language for DB2. SQL statements embedded in a User Language procedure can update a DB2 database or return selected values from DB2 to Model 204.

The following example is an SQL statement embedded in a User Language procedure:

EXEC DB2 DECLARE BAR CURSOR FOR SELECT CHA FROM DVPJB.TEST2 END EXEC

UL/DB2 program environment

The following figure shows the UL/DB2 program environment under IBM z/OS.

UL/DB2 program environment

Requirements

The requirements for the User Language/DATABASE 2 Interface are:

• IBM z/OS 1.01 or higher
• Model 204
• DATABASE 2 Version 2 Release 1 or higher
• To use a Model 204 user ID as the DB2 authorization ID, the Model 204 security interface for ACF2 must be installed.

Supported operating systems

UL/DB2 runs under only IBM z/OS. It does not run under IBM z/VM or IBM z/VSE operating systems.

Accessing DB2 address spaces

Model 204 uses the Call Attach Facility (CAF) to communicate with a single local DB2 subsystem that is on the same physical machine as Model 204.

However, this local DB2 subsystem can use the DATABASE 2 Distributed Data Facility (DDF) to communicate with one or more remote DB2 databases. These remote databases can be on the same CPU as the local database or on a different CPU.

Limitations

The following limitations apply to the UL/DB2 Interface:

• The UL/DB2 Interface is for only z/OS DB2.
• The JCL to run Model 204 must include DSNvrm.DSNLOAD in the STEPLIB in order to load DSNALI and DSNTIAR, unless the module is in the Link Lookaside Area.
• The UL/DB2 Interface is for a single machine implementation.
• There is no support for singleton SELECT statements, although singleton SELECT statements can be issued using the $SPIFY function.
• There are no system manager commands to control the subtasks.
• The number of threads, or subtasks, is defined statically.
• The Model 204 address space can have a link open to only one local DB2 subsystem.
• A maximum of ten cursors can be open simultaneously.