Deployment

Installation Process

Enhanced Definition

In the z/OS environment, deployment refers to the structured process of installing, configuring, and making available software components, applications, or system updates onto the mainframe. This typically involves moving compiled code, JCL, configuration files, and data definitions from development or test environments to production or other target systems, ensuring they are ready for execution and operational use. In the mainframe context, deployment refers to the structured process of installing, configuring, and making applications, system software, or configuration changes operational within a target z/OS environment. It involves moving tested artifacts (e.g., load modules, JCL, data definitions) from development or test stages to production or other designated environments.

Key Characteristics

- Highly Controlled and Audited: Mainframe deployments are subject to stringent change control procedures, audit trails, and approvals due to the mission-critical nature of z/OS systems and the data they process.
- Batch-Oriented: Many deployment steps involve submitting JCL jobs to allocate datasets, copy members, bind DB2 packages, install CICS resources, or execute utility programs.
- Dataset-Centric: Software components are typically stored in various types of datasets (e.g., PDS/PDSE for load modules, source code, JCL; VSAM for application data; sequential datasets for logs).
- Phased Rollout: Deployments often follow a staged approach, moving from development to test, QA, staging, and finally production environments to minimize risk.
- System Programmer Involvement: Requires deep knowledge of z/OS system services, dataset management, security (RACF/ACF2/TSS), and subsystem configurations (CICS, DB2, IMS).
- Tools-Assisted: Often utilizes specialized tools like SMP/E for system software, ISPF utilities, custom JCL, REXX scripts, or third-party change management systems (e.g., CA Endevor, IBM UrbanCode Deploy for z/OS).

Use Cases

- New Application Rollout: Installing a newly developed COBOL or PL/I application, including its load modules, JCL procedures, DB2 DDL, and CICS definitions, into a production CICS region.
- System Software Updates: Applying maintenance (PTFs/APARs) to z/OS components, CICS, DB2, or other IBM products using SMP/E.
- Configuration Changes: Deploying updates to system parameters, security rules (RACF profiles), or network definitions (VTAM/TCP/IP).
- Database Schema Changes: Implementing DDL changes for DB2 or IMS databases, which might involve creating new tables, altering existing ones, or rebuilding indexes.
- Batch Job Stream Updates: Deploying new or modified JCL procedures and associated utility programs for critical batch processing.

Related Concepts

Deployment is intrinsically linked to Change Management, ensuring that all modifications are tracked, approved, and reversible. It heavily relies on JCL for automating installation steps and Dataset Management for organizing and storing software components. It interacts with Security Systems (like RACF) to ensure proper access permissions for deployed code and data, and with Subsystems (CICS, DB2, IMS) to make applications available to users.

Best Practices:

Automate Everything Possible: Use JCL, REXX, or specialized deployment tools to automate repetitive tasks, reducing manual errors and ensuring consistency across environments.
Implement Robust Change Management: Adhere to strict change control processes, including version control, approval workflows, and comprehensive backout plans for every deployment.
Test Thoroughly in Staging: Always deploy and rigorously test changes in a non-production environment that closely mirrors production before moving to live systems.
Document Procedures: Maintain clear, up-to-date documentation for all deployment steps, configurations, dependencies, and verification procedures.
Plan for Backout: Develop and test a comprehensive backout strategy to revert to the previous stable state in case of deployment failures or unexpected issues.
Utilize SMP/E for System Software: For IBM system software and products, always use SMP/E (System Modification Program/Extended) for installation and maintenance to ensure integrity, serviceability, and proper tracking of changes.