gtpm6m0u | Main Supervisor Reference |
In an MDBF system, system programs need support facilities to access the
program or database of subsystem users in the complex.
Under MDBF, each subsystem maintains its own database, which is identified by
a subsystem database ID (DBI). All subsystem users within a
particular subsystem have the same DBI. During IPL each
subsystem (SS) and subsystem user (SSU) is assigned an
ID.
Cross subsystem access service routines use the program base ID
(PBI), database ID (DBI), and subsystem user ID (SSU ID) to service MDBF macro
requests. Normal changes to the DBI and PBI are from the basic
subsystem (BSS) to a subsystem (SS), or vice versa. System programs
should use only MDBF macros to change and manipulate these fields.
Application programs should not use MDBF macros. MDBF macros
include:
- CROSC
- CROSC permits one subsystem to access another subsystem's data or
program base. To access programs or global data, invoke the CROSC macro
in either the ECB virtual memory or the system virtual memory. To get
pools from another subsystem, use CEBIC to change the DBI and GETFC to get the
pool.
- UATBC
- Use the UATBC macro to locate information pertaining to a particular
subsystem. UATBC calculates and returns the address of a subsystem user
from a list of addresses in the subsystem user table (SSUT). UATBC then
uses the SSUT to access specific subsystem user data.
- CEBIC
- To access the database of any other subsystem, use the CEBIC macro to
change the DBI and SSU ID in an active program's ECB. The DBI and
SSU ID are preserved across CEBIC calls. Return is made to the original
subsystem and/or subsystem user.
- LEBIC
- Several tables are generated in an MDBF system. These tables are
accessed by using either the subsystem or SSU ID. To locate the proper
ID from a list of identifiers requires an index into the list. The
LEBIC macro standardizes the retrieval of these index values. Use the
LEBIC macro to obtain the index value for a specified ID, validate the ID, and
convert a specified subsystem or SSU ID to a subsystem/SSU ordinal
number.
Both CP segments and E-type programs can use CEBIC and LEBIC, however,
different input restrictions apply. See TPF General
Macros and TPF System Macros for these
restrictions and more information on all the MDBF macros.