Starting JES2, 10.2.1.1 JES2 Checkpoint, Power JES2

POWER		JES2

	Checkpoint
Queue file		Data set
	(Incl. Job &
		Output Queue

		Duplex Copy



Data file	Spool files
up to 15	up to 253
extents	data sets



Accounting	SMF data sets
File		(part of MVS)

Your starter OS/390 system has a small JES2 subsystem defined with a minimal JES2 checkpoint and spool data sets. You will have to redefine them to support your environment.

10.2.1.1 JES2 Checkpoint

Similar to the POWER Queue File (IJQFILE), JES2 uses the ²Checkpoint² data set(s) to manage its queues. Two JES2 checkpoint data sets should be allocated on different volumes to contain a copy of the JES2 job and output queues and information that must be retained across a JES2 restart. For details on the size, placement, and specification, see Chapter 4 in the OS/390 JES2 Initialization and Tuning Guide.

10.2.1.2 JES2 Spool Volumes

One or more JES2 spool data sets must also be allocated to contain a copy of job input and output, along with spooled control blocks for JES2. All spool data sets must have the same data set name and reside on DASD volumes with serial numbers starting with the same four or five characters as specified on the SPOOLDEF parameters. All spool data sets must have the same names, so there can only be one per volume and the volumes can not be DFSMS managed. For the specific size, placement, and attribute specification, see Chapter 3 in the OS/390 JES2 Initialization and Tuning Guide.

10.2.2 Starting JES2

Similar to the startup options in VSE/POWER, you can start JES2 automatically at IPL time, or the operator can enter the ²S JES2² command.

There are also two types of startup: cold start, and warm start. As with POWER, you must use the ²COLD² option when bringing up JES2 for the very first time, or when restarting JES2 with incompatible init parms. Otherwise a warm start is required to preserve the jobs and spooled data from before. There are other

210VSE to OS/390 Migration Workbook

OS/390 specifications

IBM OS/390, a versatile operating system, was a cornerstone in enterprise environments and played a pivotal role in mainframe computing. Released in the mid-1990s, OS/390 combined the strengths of IBM's MVS (Multiple Virtual Storage) with new features and enhancements, targeting scalability, reliability, and performance in demanding business applications.

One of the key features of OS/390 was its robust support for multiple users and processes. The system allowed thousands of concurrent users to access applications and data, ensuring high availability and minimizing downtime—a critical requirement for many large organizations. This scalability was supported through various enhancements in memory management and processor scheduling, enabling optimal resource allocation across diverse workloads.

OS/390 was known for its superior workload management capabilities. The Workload Manager (WLM) component allowed administrators to define service policies, specifying how system resources would be allocated according to the priority of tasks. This ensured that critical business processes received the necessary resources while less critical tasks were managed more flexibly.

Another significant characteristic of OS/390 was its commitment to security. The operating system provided comprehensive security features, including user authentication, data encryption, and auditing capabilities. This focus on security was vital for organizations handling sensitive data, ensuring compliance with regulations and safeguarding against unauthorized access.

OS/390 also supported advanced technologies that facilitated integration and development. The system included features like the IBM CICS (Customer Information Control System) for transaction processing and IMS (Information Management System) for database management. These technologies allowed organizations to build robust, high-performance applications tailored to specific business needs.

The ease of network integration was another strength of OS/390. With the advent of the Internet and global connectivity, OS/390 systems could easily interface with various network protocols, enabling businesses to operate in a connected world. This inclusion paved the way for many organizations to expand their capabilities and offer new services, driving digital transformation.

In conclusion, IBM OS/390 represented a significant advancement in mainframe technology, combining scalability, security, and robust workload management. Its rich feature set and support for critical enterprise applications solidified its role as a vital component of many organizations' IT infrastructures, ensuring they could meet their operational challenges head-on while supporting future growth. As technology continues to evolve, the legacy of OS/390 remains influential in the realm of computing.

IBM OS/390 manual Starting JES2, 10.2.1.1 JES2 Checkpoint, 10.2.1.2 JES2 Spool Volumes, Power JES2

Models: OS/390

POWER

JES2

10.2.1.1 JES2 Checkpoint

10.2.1.2 JES2 Spool Volumes

10.2.2 Starting JES2

210VSE to OS/390 Migration Workbook

OS/390 specifications