31.4 JES2 Diagnosis

There are some JES2 mechanisms that can be used for problem determination.

$TRACE: JES2 internal tracing can be activated via $S TRACE; $T TRACEDEF; $P TRACE commands. These are typically requested by IBM service personnel.

SYMREC: Symptom records are recorded in the LOGREC file for some JES2 internally discovered problems. Use EREP to format these entries.

HASP088 message: When JES2 terminated abnormally, a HASP088 message is generated. This multi-line WTO has registers at ABEND, a traceback of program linkage leading up to the error, and of course the reason for the termination.

Analysis of maintenance level: The maintenance level of a given module as well as its memory address can be determined via $D MODULE(name). This typically will be requested by IBM service personnel.

31.5 SLIP

SLIP commands are a powerful tool that can be used to either take an SDUMP or write trace records to GTF. Some of the SLIP commands are PER (program event recording) such as instruction fetch and successful branch and may cause CPU degradation depending upon how they are used. SLIP provides additional functionality beyond what the VSE SDAIDS does. SLIP commands are generally entered by a system programmer at an operator console. If the SLIP command causes trace data to be written, then GTF needs to be started for the trace data to be recorded.

31.6 Performance Tools

RMF is provided with OS/390, in addition there are several vendor performance monitors.

RMF provides three levels of performance monitoring:

MONITOR I - records data to SMF that is used for performance and capacity analysis. Data is formatted via an RMF batch program or by other products such as SLR or SAS.

MONITOR II - runs under TSO and provides an interactive view of the OS/390 system (CPU, paging, storage, dispatching).

MONITOR III - a powerful interactive tool that monitors the OS/390 system for bottlenecks in system throughput and provides a point and shoot view of overall and subsystem performance. Current interval and historical interval data is provided.

31.7 LOGREC

The LOGREC data set is functionally equivalent to the VSE recorder file. In addition to hardware errors OS/390 records software errors to this data set. This provides valuable information in the initial problem determination phase of diagnosing a problem. EREP is normally used to extract the required records. In

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IBM OS/390 manual 31.4 JES2 Diagnosis, Slip, Performance Tools

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.