gtps4m0pSystem Generation

TPF Control Program Area

The TPF core resident control program is assembled and link-edited by SIP. The link-edited version is known as CPS0vv, where vv is its version number, and it is assigned to main memory to control the online execution of the system. It also resides on the online files for the purpose of system restart in a location known as the core image area. It consists of a set of required and optional control sections (CSECTs). Which CSECTs are included is based upon user selection of SIP macros and macro parameters for the particular system configuration being generated. Several CSECTs are released as object code and SIP only reassembles these if requested by the user. Typically, each CSECT, in some cases more than one, supports a major functional area (for example, tape support, unit record, SNA, and so on).

The control program serves all subsystems in an MDBF environment. It is part of the BSS. The size of the control program is dependent upon the system configuration selected. Some of the CSECTs are optional and are only required if related hardware is included in the system configuration.

The size of many of the individual CSECTs of the control program, both optional and mandatory CSECTs, is also influenced by the fact that Basic Assembler Language (BAL) conditional assembly language (the AIF statement) is also used to include/exclude lines of code and tables. SIP first produces PDS members SYGLB and SYSET which contain global variable statements/values and are then copied (via the assembler COPY statement) by the segments of the various CSECTs when the control program is assembled by SIP. These values are obtained/calculated from user-coded SIP input. The purpose is to resolve user/installation variables at assembly time.

The control program nucleus employs the following main storage boundaries:

The size of the control program is approximately 970K.

At the end of each CSECT is a macro that rounds each CSECT. This allows the next CSECT to start on an easily identified boundary and provides a patch area within each CSECT.

There is also a particular CSECT, CPLKMP, which contains a table which has the name including version number of each CSECT and its starting address and length. This CSECT is provided to give easy access to this information. It appears in a dump of the system for use when debugging.

Figure 9. Virtual Storage Layout


Note:
TPF's virtual address spaces makes it impossible to use a full 2 gigabytes of real memory.