CSL configuration examples

Typically, when an IMS control region (DL/I, DBRC, dependent regions) requires the use of the CSL, SCI, OM, and RM are all required. However, different configurations are possible for the CSL in an IMSplex. For example, you might include ODBM or omit RM in your CSL configuration.

The basic CSL components are the CSL managers, which are:

Open Database Manager
The Open Database Manager (ODBM) is optional in an IMSplex. You can define additional ODBMs in the IMSplex to enhance performance and availability.
Operations Manager
At least one OM must be available in the IMSplex. You can define additional OMs in the IMSplex to enhance performance and availability.
Resource Manager
If any IMS in the IMSplex requires RM services, at least one RM must be available when the IMSplex is initialized. You can define additional RMs in the IMSplex for performance and availability enhancements if a resource structure is used. However, only one RM can be started in an IMSplex if a resource structure is not used. You can configure your IMSplex without an RM and use type-2 commands.

If an IMSRSC repository is enabled in the IMSplex, a CSL configuration with RM is required.

Structured Call Interface
One SCI is required on each z/OS® image where an IMSplex member is running. Only one SCI is allowed on each operating system image for a given IMSplex.

Sample IMSplex configuration with CSL

The following figure illustrates a sample IMSplex configuration that includes the CSL, a SPOC, and automated procedures.

  • The OS image includes addresses spaces for ODBM, OM, SCI, RM, an IMS control region, IMS Connect, and IMS CQS.
  • The OS image shares a coupling facility and databases.
  • A SPOC application, an automation application, a master terminal, and an end user terminal all access the OS image.
  • The Open database resource adapters and APIs are also shown accessing the OS image through IMS Connect, the TCP/IP gateway for IMS.
Figure 1. Sample IMSplex configuration with CSL
begin figure description. This figure is described in the surrounding text. end figure description.

To obtain the fastest communication, define an OM and RM on each z/OS image; an IMSplex component can communicate more quickly with an OM or RM on the same z/OS image as that component rather than an OM or RM on a different z/OS image. However, this configuration also increases the number of address spaces on each z/OS image, which can create a more complex operating environment.

Note: If only one RM and only one OM are defined across an IMSplex, there is no backup to perform that manager's work in case of failure.
Recommendation: Define more than one RM, OM, and SCI across an IMSplex.

IMSplex minimum CSL configuration

The following figure illustrates the minimum configuration possible for the CSL in an IMSplex. Each OS image has an IMS control region and an SCI; in addition, the first OS image also has an OM, but no RM. RMENV=NO was specified on the startup parameter.

Figure 2. IMSplex minimum CSL configuration
begin figure description. This figure is described in the surrounding text. end figure description.

In the figure, each z/OS image has a separate SCI since each has a distinct IMS control region. OM can reside on one z/OS image and still be used by other images in the IMSplex.

IMSplex mixed version CSL configuration

The following figure illustrates a more complex configuration having multiple versions of IMS within the IMSplex.

  • Operating System 1 has IMS Version 12 control regions and is running OM and RM
  • Operating System 2 has IMS Version 13 control regions, an ODBM, and an OM
  • Operating System 3 has an IMS Version 11 control region
All three OS images share the coupling facility. Within the coupling facility is a resource structure. Therefore, an additional RM could be defined in another OS image.
Figure 3. IMSplex mixed version CSL configuration
begin figure description. 3 Operating systems shown; the first has IMS Version 12 control region, SCI, OM, RM, and CQS. The second has IMS 15 control region, SCI, RM, and CQS. The third has IMS Version 11 control region and CQS batch region. All three share a coupling facility with DB sharing, message queue, and resource structure. end figure description.

IMSplex DBCTL CSL configuration

The following figure illustrates the configuration of the Common Service Layer in a DBCTL environment. Here, three OS images each have an IMS DBCTL control region. All have an SCI and an OM. Two have an ODBM. Only one RM is allowed in the IMSplex, here in OS1, because no resource structure is defined.

Recommendation: Define a resource structure for DBCTL.
Figure 4. IMSplex DBCTL CSL configuration
begin figure description. This figure is described in the surrounding text. end figure description.

In the figure, an OM is defined in each OS image to enhance overall system performance. If you do not use global online change, neither RM services nor an RM address space is required. In such a configuration, the CSL includes SCI and OM.

IMSplex minimum ODBM configuration

The following figure illustrates a minimum configuration for ODBM in an IMSplex that include three IMS systems. Each OS image has an IMS control region, an SCI, and an ODBM; in addition, the first OS image also has an OM, which is required by ODBM, but no RM. RMENV=NO was specified on the startup parameter.

The ODBM configuration shown is not a data sharing environment. Each IMS system manages its own databases separately.

Also, the databases on operating system 3 cannot be accessed by ODBM clients, such as the IMS Universal drivers, because an instance of ODBM is not running on operating system 3.

Figure 5. IMSplex minimum ODBM configuration
begin figure description. This figure is described in the surrounding text. end figure description.

In the figure, each z/OS image has a separate SCI since each has a distinct IMS control region. OM can reside on one z/OS image and still be used by other images in the IMSplex. An instance of ODBM must be active on each z/OS image that contains databases to which ODBM clients require access.

Shared queues in an IMSplex without a CSL

In the following figure, three OS images are each defined with an IMS control region and IMS CQS. Each is associated with a Master Terminal Operator (MTO) console. All three OS images share a coupling facility that includes database sharing structures and a message queue structure. No CSL manager address spaces are defined.

This figure illustrate what a shared queues IMSplex environment looks like without a CSL.

Figure 6. Shared queues in an IMSplex without a CSL
begin figure description. This figure is described in the surrounding text. end figure description.

Shared queues in an IMSplex environment with a CSL

In the following figure, three OS images are defined. Each is identical, having an IMS control region, IMS CQS, and all CSL managers (SCI, OM, and RM). The three OS images share the coupling facility, which includes database sharing structures, a message queue structure, and a resource structure. A SPOC application can access any of the OS images.

This figure illustrates what a shared queues IMSplex environment looks like with a CSL.

Figure 7. Shared queues in an IMSplex environment with a CSL
begin figure description. This figure is described in the surrounding text. end figure description.

IMSplex configuration with an IMSRSC repository

The following figure illustrates a sample IMSplex configuration that includes an IMSRSC repository.

The following components comprise the repository: CSL, OM, RM, SCI, TSO SPOC or an automation application program, a Repository Server (RS), RS catalog repository data sets, and the IMSRSC repository data sets.

Optionally, the configuration can include a CQS address space and a z/OS cross-system coupling facility with a resource structure. CQS is required if RM is using the resource structure.

Figure 8. IMSplex configuration with an IMSRSC repository
Begin figure description. The IMS control region uses SCI to communicate with OM and RM. RM communicates directly with RS and CQS. RS is connected to the repository sets of data sets. A SPOC or automation program is connected to OM. End figure description.

IMSplex single system CSL configuration

In a single system IMSplex environment, each address space of the Common Service Layer is defined in a single OS image. This simple configuration is shown in the following figure. The OS image is defined with multiple IMS control regions, and one SCI, RM, OM, and ODBM.

Figure 9. IMSplex single system CSL configuration
begin figure description. This figure is described in the surrounding text. end figure description.