HPlogo MPE/iX Intrinsics Reference Manual > Chapter 2 Intrinsic Use

Additional Capabilities Required

MPE documents

Complete PDF
Table of Contents
Index

Edition 7 E0701 ♥
Edition 7 E0300
Edition 6 E0195

Most system intrinsics do not require additional capabilities to access operating system features. However, if an intrinsic requires the operating system to check for an additional capability at program load and/or run time, that capability must be assigned prior to running the program.

Table 2-6 "Additional Capabilities Required" lists additional capabilities and the assignments required by some intrinsics.

NOTE: A system manager or account manager must assign the capabilities to the group where the program file resides or to the user running the program. You must assign PH, DS, MR, and PM capabilities to the program file at link time using the caplist parameter of the LINK command.

Table 2-6 Additional Capabilities Required

Capability Required Assignment To
Data segment management (DS)The program file and the group in which that file resides
User logging (LG)The user running the program
Multiple RIN (MR)The program file and the group in which that file resides
Nonshareable device (ND)The user running the program
System supervisor (OP)The user running the program
Process handling (PH)The program file and the group in which that file resides
Privileged mode (PM)The program file and the group in which that file resides
Programmatic sessions (PS)The user running the program

The operating system performs two capability checks prior to executing the program. The checks must succeed before the program can run:

  • At load time, the file system checks the user capability list against the account-level, group-level, and file-level security provisions for the program file and all referenced executable library (XL) files.

  • At load time, the loader checks the program file's capability list against the capability list for the group in which the program file resides. If the program is located in a temporary file, the loader checks the program file's capability list against the capability list for the user who is running the program. In this case, the capability must be assigned to the user in addition to (or instead of) the group.

A third capability check occurs at run time when the program executes the code of an intrinsic that requires a capability. The intrinsic checks either the program file (for DS, MR, ND, PH, or PM) or the user (for LG, OP, or PS). If the operating system does not find the correct capability, the program aborts.

The operating system optional capabilities, and what they allow you to do, are explained below.

DS Capability

The data segment management (DS) capability allows you to create and access extra data segments from processes during a job or session.

LG Capability

The user logging (LG) capability provides a flexible transaction-logging capability that allows you to record additions and modifications to your database and subsystem files on either tape or disk. If the database is lost, the logging tape or disk file facilitates recovery of the lost transactions.

MR Capability

The multiple resource identification number (MR) capability allows you to simultaneously lock as many global resource identification numbers (RINs) as desired.

ND Capability

The nonshareable device (ND) capability allows you to use devices other than terminals, discs, and spooled devices (except for the standard job/session input and list devices). If the device is nonspooled, the user has absolute control of the device.

OP Capability

The system supervisor (OP) capability allows you to optimize the performance of the system and to record additions and modifications to your databases and subsystem files.

PH Capability

The process handling (PH) capability allows you to do the following programmatically:

  • Create and delete processes

  • Activate and suspend processes

  • Send mail between processes

  • Change process scheduling

  • Get existing process information

PM Capability

The privileged mode (PM) capability allows you to access all operating system routines and data structures. The operating system protects privileged users from executing at the same privilege level as the operating system. This prevents privileged users from accessing certain instructions used by the operating system to control the hardware. There are two ways to acquire privileged mode:

  • If the routine should always run in privileged mode, use the execution-privilege option of the appropriate compiler and designate the execution level as 2. (Refer to your programming language reference manual for more details.)

  • If the routine requires privileged mode only on a selective basis, it is safer to obtain an execution level of 2 only where necessary. To do this, invoke the GETPRIVMODE intrinsic.

CAUTION: The normal checks and limitations that apply to standard users are bypassed in privileged mode. A privileged mode program can destroy file integrity and the operating system software. Hewlett-Packard will investigate and attempt to resolve problems resulting from the use of privileged mode code. This service, which is not provided under the standard service contract, is available on a time and materials billing basis. Hewlett-Packard will not support, correct, or attend to any modification of the operating system software.

PS Capability

Programmatic sessions (PS) capability allows programmatic creation of sessions on any terminal on the system.



Error Handling

Chapter 3 Intrinsic Tasks