大型机简答题考生必备
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2013-01-13
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1.List several defining characteristics of the z/OS operating system.
The use of address spaces in z/OS holds many advantages: Isolation of private areas in
different address spaces provides for system security, yet each address space also provides a
common area that is accessible to every address space.
The system is designed to preserve data integrity, regardless of how large the user population
might be. z/OS prevents users from accessing or changing any objects on the system, including
user data, except by the system-provided interfaces that enforce authority rules.
The system is designed to manage a large number of concurrent batch jobs, with no need for
the customer to externally manage workload balancing or integrity problems that might otherwise
occur due to simultaneous and conflicting use of a given set of data.
The security design extends to system functions as well as simple files. Security can be
incorporated into applications, resources, and user profiles.
The system allows multiple communications subsystems at the same time, permitting unusual
flexibility in running disparate communications-oriented applications (with mixtures of test,
production, and fall-back versions of each) at the same time. For example, multiple TCP/IP stacks
can be operational at the same time, each with different IP addresses and serving different
applications.
The system provides extensive software recovery levels, making unplanned system restarts
very rare in a production environment. System interfaces allow application programs to provide
their own layers of recovery. These interfaces are seldom used by simple applications—they are
normally used by more sophisticated applications. The system is designed to routinely manage
very disparate workloads, with automatic balancing of resources to meet production requirements
established by the system administrator.
The system is designed to routinely manage large I/O configurations that might extend to
thousands of disk drives, multiple automated tape libraries, many large printers, large networks of
terminals, and so forth.
The system is controlled from one or more operator terminals, or from application
programming interfaces (APIs) that allow automation of routine operator functions. The operator
interface is a critical function of z/OS. It provides status information, messages for exception
situations, control of job flow, hardware device control, and allows the operator to manage
unusual recovery situations.
2.What is a data set? What types of data sets are used on z/OS?
A data set is a collection of logically related data records stored on one disk storage volume
or a set of volumes. A data set can be, for example, a source program, a library of macros, or a file
of data records used by a processing program. You can print a data set or display it on a terminal.
The logical record is the basic unit of information used by a program running on z/OS.
sequential, partitioned, and VSAM
3.What is the difference between JCL and a JCL PROC? What is the benefit of using a JCL
PROC?
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