Compaq COBOL
User Manual

Chapter 15
15	Optimizing Your Compaq COBOL Program
15.1	Specifying Optimization on the Compiler Command Line (Alpha)
15.2	Specifying Alignment of Data for Optimum Performance (Alpha)
15.3	Using COMP Data Items for Speed
15.4	Other Ways to Improve the Performance of Operations on Numeric Data
15.4.1	Mixing Scale Factors and Data Types
15.4.2	Limiting Significant Digits
15.4.3	Reducing the Compexity of Arithmetic Expressions
15.4.4	Selection of Data Types (OpenVMS)
15.5	Choices in Procedure Division Statements
15.5.1	Using Indexing Instead of Subscripting
15.5.2	Using SEARCH ALL Instead of SEARCH
15.5.3	Selecting Hypersort or SORT-32 for Sorting Tasks
15.5.4	Minimizing USE Procedures with LINKAGE SECTION References
15.6	I/O Operations
15.6.1	Using the APPLY Clause
15.6.1.1	Using the PREALLOCATION Phrase of the APPLY Clause (OpenVMS)
15.6.1.2	Using the EXTENSION Phrase of the APPLY Clause (OpenVMS)
15.6.1.3	Using the DEFERRED-WRITE Phrase of the APPLY Clause (OpenVMS)
15.6.1.4	Using the FILL-SIZE ON Phrase of the APPLY Clause (OpenVMS)
15.6.1.5	Using the WINDOW Phrase of the APPLY Clause (OpenVMS)
15.6.2	Using Multiple Buffers
15.6.3	Sharing Record Areas
15.6.4	Using COMP Unsigned Longword Integers
15.7	Optimizing File Design (OpenVMS)
15.7.1	Sequential Files
15.7.2	Relative Files
15.7.2.1	Maximum Record Number (MRN)
15.7.2.2	Cell Size
15.7.2.3	Bucket Size
15.7.2.4	File Size
15.7.3	Indexed Files
15.7.3.1	Optimizing Indexed File I/O
15.7.3.2	Calculating Key Index Levels
15.7.3.3	Caching Index Roots
15.8	Image Activation Optimization (Tru64 UNIX)
Chapter 16
16	Managing Memory and Data Access
16.1	Managing Memory Granularity (Alpha)
16.2	Using the VOLATILE Compiler Directive (Alpha)
16.3	Aligning Data for Performance and Compatibility (Alpha)
16.3.1	Data Boundaries (Alpha)
16.3.2	Data Field Padding (Alpha)
16.3.3	Alignment Directives, Qualifiers, and Flags (Alpha)
16.3.4	Specifying Alignment at Compile Time (Alpha)
16.4	Using Alignment Directives, Qualifiers, and Flags (Alpha)
16.4.1	Order of Alignment Operations (Alpha)
16.4.2	Nesting Alignment Directives (Alpha)
16.4.2.1	SYNCHRONIZED Clause
16.4.3	Comparing Alignment Directive Effects
Appendix A
Appendix A	Compiler Implementation Specifications
Appendix B
Appendix B	Compaq COBOL on Three Platforms: Compatibility and Migration
B.1	Compatibility Matrix
B.2	Differences in Extensions and Other Features
B.3	Command-Line Qualifiers (Options or Flags)
B.3.1	Qualifiers and Flags Shared by Compaq COBOL on Alpha and VAX
B.3.2	Alpha-Specific COBOL Qualifiers and Flags
B.3.3	Qualifiers Only on Compaq COBOL for OpenVMS VAX
B.4	Compaq COBOL Behavior Differences on VAX and Alpha
B.4.1	Program Structure Messages
B.4.2	Program Listing Differences
B.4.2.1	Machine Code
B.4.2.2	Module Names
B.4.2.3	COPY and REPLACE Statements
B.4.2.4	Multiple COPY Statements
B.4.2.5	COPY Insert Statement
B.4.2.6	REPLACE and COPY REPLACING Statements
B.4.2.7	DATE COMPILED Statement
B.4.2.8	Compiler Listings and Separate Compilations (OpenVMS)
B.4.3	Output Formatting
B.4.4	Compaq COBOL Statement Differences on Alpha and VAX
B.4.4.1	ACCEPT and DISPLAY Statements
B.4.4.2	LINAGE Clause
B.4.4.3	MOVE Statement
B.4.4.4	SEARCH Statement
B.4.5	System Return Codes
B.4.6	Diagnostic Messages
B.4.7	Storage for Double-Precision Data Items
B.4.8	File Status Values
B.4.9	RMS Special Registers (OpenVMS)
B.4.10	Calling Shareable Images
B.4.11	Sharing Common Blocks (OpenVMS)
B.4.12	Arithmetic Operations
B.5	Compaq COBOL Differences Between Releases and Across Operating Systems
B.5.1	REWRITE
B.5.2	File Sharing and Record Locking
B.5.3	VFC File Format
B.5.4	File Attribute Checking (Tru64 UNIX)
B.5.5	Indexed Files
B.5.6	RMS Special Register References in Your Code
B.6	File Compatibility Across Languages and Platforms
B.7	LIB$INITIALIZE Interaction Between C and COBOL
B.8	Reserved Words
B.9	Debugger Support Differences
B.10	DECset/LSE Support Differences
B.11	DBMS Support
B.11.1	Compiling on Tru64 UNIX
B.11.2	Multistream DBMS DML