CRE Programmer's Guide

Compiling and Binding Programs for the TNS CRE
Common Run-Time Environment (CRE) Programmer’s Guide—528146-004
3-5
CRE Data Blocks
CRE Data Blocks
When a compilation unit contains a main procedure, the C compilers allocate and
initialize special data blocks required by the CRE. When a compilation unit contains a
main procedure and you have specified an ENV COMMON directive, the TNS COBOL,
FORTRAN, and TAL compilers allocate and initialize these special data blocks.
Table 3-5
on page 3-5 lists the special data blocks.
Binding Programs for the CRE
Binder categorizes the ENV directive parameters into three groups: OLD, NEUTRAL,
and COMMON. For the most part, these groups match the various ENV options.
Refer to Compiling Programs for the CRE
on page 3-1 for a complete discussion of the
ENV directive. Table 3-6
on page 3-5 shows how Binder classifies object files into one
of three groups depending on the compiler version or specified ENV option.
Table 3-5. Common Run-Time Environment Data Blocks
Data Block Name Description
Basic control block #CRE_GLOBALS Located at G[0] and G[1] of the user data
segment.
Master control block #MCB If a program contains FORTRAN routines, the
Binder program allocates the MCB in the upper
32K area of the user data segment, regardless of
the value of the HIGHCONTROL FORTRAN
directive.
CRE run-time heap #CRE_HEAP A run-time heap required by CRE functions. It is
the last block in the upper 32K area of the user
data segment.
Table 3-6. Binder Grouping of ENV Directive Parameters (page 1 of 2)
Binder Group Language Generated by
OLD C C-series compilers by default
COBOL C-series compilers by default
D-series compilers by default
D-series compilers with ENV OLD specified
FORTRAN C-series compilers by default
D-series compilers by default
D-series compilers with ENV OLD specified
TAL D-series compilers with ENV OLD specified
COMMON C D-series compilers by default
D-series compilers with ENV COMMON specified
COBOL D-series compilers with ENV COMMON specified
D-series compilers with ENV LIBRARY specified