StorageTek 6 manual Task Management, Job Management, Processor Management, Communication

Task Management

Multi-tasking is provided by the SCP to support the MVS-type task requests such as POST, WAIT, ATTACH, etc. that the HSC expects. All modules are made resident at the time of initialization. Also included in this component is the processing of System Management Facility (SMF) records for output to a spool file.

Job Management

Most utilities are executed within the SCP environment as batch jobs punched by other virtual machines. Special job statements define both the resources to be used and the parameters to be passed to the desired program.

Processor Management

This component handles the resources of the virtual processor, including:

•interrupt handlers

•timer management

•IUCV paths and messages

•event tracing.

This component also handles authorization checking and PSW mode changing. Interrupts consist of common processing, a first level handler which usually sorts out the interrupt subtypes, and a second level handler which does the bulk of the processing. Timer services include the TOD clock, the TOD clock comparator, and the CPU timer. Tracing includes an internal table and a task which writes records to a spool file.

Communication

Standard MVS-type WTO/R and related operator communications are also supported, with limitations on the routing and descriptor codes. The QEDIT interface, ECBs, and various queues provide for inter-task communication.

Inter-Machine Communication

The Inter-User Communication Vehicle (IUCV) is a closed-loop technique used in VM to communicate between users. A user sends an IUCV message and waits for a reply. This service is used to transfer data between the HSC and the TMS.

Additionally, IUCV is used to access the BLOCKIO and MESSAGE system services. The message service (*MSG) is used to intercept SMSG communications from operators.CP DASD BLOCKIO forms the foundation of the SCP BDAM access method. BLOCKIO reads and writes data to any DASD device with device independence, but the SCP must be aware of the device type, especially when the data set is shared with an MVS host.

8VM/HSC 6.0 System Programmer’s Guide

1st ed., 6/30/04 - 312579601