Memorex LOCK - VERSION 2-24 Informacje Techniczne Pobierz pdf (Strona 48)

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Allocating Logical Unit Blocks (LUB)

1-30 User Reference

Use Pursuant to Company Instructions

Allocating Logical Unit Blocks (LUB)

Description The VSE Logical Unit Blocks (LUB) connects the logical unit (SYS

number) in a file definition DTF with the physical device address (cuu)

that controls the dataset.

When a disk or tape dataset is opened, if the SYS number specified in the

program is already in use, the LUB allocation feature assigns logical units

for tape and disk devices. This eliminates potential conflicts in SYS

number assignments when:

 A program or job stream uses the same SYS number for two

different datasets and the datasets are stored on two different

DASDs or tape units.

 The requested SYS number is permanently assigned to another

device.

The LUB allocation feature reassigns new SYS numbers to both datasets

and continues processing without interruption. In addition, LUB

allocation allows BIM-EPIC to write multiple extents for a single dataset

on separate disk volumes to more efficiently use the disk pooling feature.

When a dataset is opened and the SYS number is already in use,

BIM-EPIC selects an unused SYS number. For disk datasets, BIM-EPIC

begins assigning SYS numbers with the number specified in the

DSKLUB configuration option. For tape datasets, BIM-EPIC begins with

the number specified in the TAPLUB configuration option.

In most cases, LUB allocation is automatic. However, in some cases,

LUB allocation is inhibited automatically. You can also inhibit the LUB

allocation using JCL parameters. See Chapter 5, “

BIM-EPIC TLBL and

DLBL Statements,” for additional information.

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