Software Installation

z/OS

Enhanced Definition

In the z/OS environment, software installation is the structured process of deploying new or updated program products, operating system components, or middleware onto the system. It involves allocating necessary datasets, loading program libraries, configuring system parameters, and making the software available for execution. This highly controlled process ensures system integrity and proper functionality.

Key Characteristics

- SMP/E (System Modification Program/Extended): The primary and indispensable tool for managing the installation, maintenance, and tracking of all IBM and many vendor software products on z/OS.
- Target and Distribution Libraries: Software is typically installed into DLIBs (Distribution Libraries) and then applied to TLIBs (Target Libraries) for execution, allowing for easier backout and maintenance.
- JCL-driven: Most installation steps, particularly those involving SMP/E, are executed via Job Control Language (JCL) jobs, which define the datasets, utilities, and execution parameters.
- Multi-phase Process: A typical SMP/E installation involves phases like RECEIVE (transferring software into SMP/E's global zone), APPLY (installing into target libraries), and ACCEPT (making the installation permanent in distribution libraries).
- Configuration Intensive: Post-installation often requires extensive configuration updates to system datasets such as SYS1.PARMLIB, SYS1.PROCLIB, VTAMLST, and RACF definitions.
- IPL Requirement: Major system software installations or upgrades (e.g., new z/OS versions, significant middleware updates) frequently necessitate an IPL (Initial Program Load) to activate the changes system-wide.

Use Cases

- New Product Deployment: Installing a new IBM product like CICS Transaction Server, DB2 for z/OS, IMS, or WebSphere MQ, or a third-party vendor application.
- Operating System Upgrades: Migrating from one version of z/OS to a newer one (e.g., z/OS V2.4 to V2.5), which is a complex and multi-stage installation effort.
- Applying Maintenance: Installing PTFs (Program Temporary Fixes) or APARs (Authorized Program Analysis Reports) to resolve bugs, apply security patches, or add minor enhancements.
- Custom Application Deployment: While not typically using SMP/E, the concept extends to deploying custom COBOL or Assembler application load modules and associated datasets into production libraries.
- Disaster Recovery Setup: Installing a replica of the production software environment on a recovery system to ensure business continuity.

Related Concepts

Software installation is a foundational activity for System Programming and System Administration on z/OS. It relies heavily on JCL for executing installation steps and SMP/E for managing the software lifecycle. Properly installed software forms the operational base for all z/OS subsystems (CICS, DB2, IMS) and user applications. It is intrinsically linked to System IPL processes, PARMLIB configuration, and RACF security definitions, ensuring the stability and functionality of the entire z/OS ecosystem.

Best Practices:

Test in a Dedicated LPAR: Always perform new software installations or significant maintenance in a non-production test LPAR first, followed by thorough testing, before deploying to production.
Backup Critical Libraries: Before any major installation or maintenance, ensure comprehensive backups of SMP/E datasets, SYS1.LINKLIB, SYS1.LPALIB, and other critical system libraries.
Review Documentation and PSP: Meticulously read and follow all vendor installation guides, PSP (Preventive Service Planning) information, and README files for prerequisites and known issues.
Plan for Downtime: Schedule installations during off-peak hours and plan for potential system IPLs, subsystem restarts, or application outages as required.
Use SMP/E USERMODs: For custom modifications or local fixes, create USERMODs using SMP/E BUILDMCS to ensure they are properly tracked and can be easily reapplied during future upgrades.