Paqe of GC20-1807-7 As Updated April 1, 1981 by TNL GN25-0829 • I/O Interrupt Work Area IOSECT (X'1620') is a work area for the I/O interrupt
oldest and newest PSW and CSW are saved. Also, there
save area.
handler. The
is a register • Program Check Interrupt Work Area PGMSECT (X'16BO') is a work area for the program check
handler. The old PSW and the address of register 13 save
stored in PGMSECT. • SVC Work Area
interrupt
area are SVCSECT (X'1748') is a work area for the SVC interrupt handler. It
also contains the first four register save areas assigned. The SFLAG (X'1758') indicates the mode of the called routine. Value of __ X'80' X'40' X'20' X'Ol' Description SVC protect key is zero
Transient area routine
Nucleus routine
Invalid reentry flag
Also, the SVC abend code, SVCAB, is located at X'1751'. • Simulated CVT (Communications Vector Table)
The CVT, as supported by CMS, is CVTSECT (X'lCC8'). Only the fields
supported by CMS are filled in. • Active Device Table and Active File Table
For file system problems, examine the ADT (Active Device Table), or 1FT (Active File Table) in NUCON. REGISTER USAGE In order to trace control blocks and modules, it is important to know
the CMS reqister usaqe conventions. GRl GR12
GR13
GR14
GR15 Address of the PLIST proqram's entry point
Address of a 12-doubleword work area for an SVC call
Return address
Program entry point or the return code
The preceding information should help you to read a eMS dump. If it
becomes necessary to trace file system control blocks, refer to Figure
37 in "Part 3. Conversational Monitor System" for more"information. With a dump, the control block diagrams, and a CMS load map you should be
able to find the cause of the abend.
72 IBM VM/370 System Guide
Part 2. Control Program (CP) Part 2 contains the following information: • Introduction to VM/370 • Program States • Using Processor Resources • Interruption Handling • Functional Information • Performance Guidelines • Virtual Machine Assist Feature • VM/370 Extended Control-Program Support • Performance Observation and Analysis • Accounting Information • Generating Named Systems and Saving Systems • The Virtual Machine Communication Facility • VM/VS Handshaking • Timers • DIAGNOSE Instruction • CP Conventions • How To Add a Console Function • How To Add a New Print or Forms Buffer Image
Part 2. Control Program (CP) 73
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