//PAUSE mount tape 123456 on an available drive.

//ASSGN SYS005,CUU

-or -

//ASSGN SYS005,Drive

The operator gets an error message and enters the correct tape assignment, such as:

// ASSGN SYS005,481

Another example is TLBL without VOLSER or a known invalid VOLSER.

// TLBL 999999

Forcing error conditions in VSE JCL that require operator intervention becomes a simple tape management method.

IGNORE, DELETE and NEWTAP are replies that the operator can use to answer the messages.

IGNORE IGNORE can be used when the data set name in the JCL does not match the data set name on the tape. IGNORE says go ahead and read it anyway. It acts as a BLP (Bypass Label Processing) in OS/390. This allows tapes with any labels or no labels to be processed without label verification.

Another approach is to leave the data set name blank which allows whatever is on the drive to be read.

DELETE DELETE is used to create a new file disk when files already exist in these extents. Using DELETE will overlay the previous extents. DELETE can also be used to overwrite extents when someone has used your extent.

NEWTAP NEWTAP is used to unload the volume currently mounted on the drive and allow the operator to mount another volume.

4.3.3.3 Comment Lines in the JCL

Comment lines can be inserted in the VSE JCL, wherever a valid JCL is allowed. Comment lines that start with an asterisk are displayed on the console and, if option LOG is set, the message is also written to SYSLST.

To have comments in the VSE JCL not written to the console use ′ / *instead of

*′. Exercise caution as to where they are placed because ′/ *still means end of data. Some people also accomplish this by using ′/.′. What is important is that

the first word must be a valid JCL label.

The MVS JCL offers no possibility to have the comments written to the console; comment lines are only written to the jobs output.

4.3.3.4 PAUSE Statement

The PAUSE statement provides the ability to halt job execution and wait for operator intervention. VSE comment lines (with an asterisk in position 1) can be used before a PAUSE statement to display multi-line messages to the operator. See 4.5.1, ªSample VSE JCLº on page 92 where there is an example of a multiple line message being sent to the console with a comment line and a PAUSE to send a message to the operator and wait.

Chapter 4. Job Control Language (JCL) Differences and Considerations 77

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IBM OS/390 manual Comment Lines in the JCL, Pause Statement, Assgn SYS005,CUU

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.