Welcome to the IBM Rational PL/I community. Here you will find the latest technical and business information, and educational information about PL/I and related z/OS and AIX topics including IMS, CICS, and Rational Developer for System z.
PL/I has complex rules for how structures are mapped and for when padding is inserted.
However, it can be important to know when there is padding in a structure (for example,
if you pass that structure to a program compiled by a language, such as C or COBOL,
that may map the structure differently).
With Enterprise PL/I 4.1, if you specify the new NOPADDING suboption to the compiler's
RULES option, the compiler will issue an E-level message for any structure that contains
RULES(NOPADDING) is also useful in detecting... [More]
Want to experience PL/I for AIX, productive and powerful development environment for building PL/I applications. Check out these features in PL/I for AIX, V3.1: Provides improved performance via both front-end changes and back-end optimizer enhancements Provides an improved debugger that enables you to conveniently debug programs form your windows-based workstation Improves the MACRO preprocessor Provides improved support for SQL and CICS Leverages productivity with new and improved built-in functions Increases quality control with new and... [More]
In the previous blog entry we showed how Character Large Objects (CLOBs)
can be manipulated with LOB locators. In this blog we will discuss
the use of LOB file references.
LOB file reference variables are also very useful when working with
LOBs. The are used to import or export data between a LOB column and
an external file outside the DB2 system.
The benefits of using LOB file reference variables are that they:
- use less CPU time than moving LOB data with a host variable
because the movement of the data would not be overlapped... [More]
Do you want to prove the depth of your PL/I knowledge to a prospective employer? Or do you
want to verify the PL/I skills of a company to whom you might outsource your PL/I code?
The PL/I certification , developed jointly by IBM and representatives from PL/I
companies from Europe and the US, can help with these and similar tasks.
IBM PL/I professional certification site you will find that there are two certification levels for PL/I: one for the general PL/I programmer in your team and a harder test
for the leader of that PL/I... [More]
Webcast Join our experts, Ray Jones, Vice President, IBM System z® Software, and Kevin Stoodley, IBM Fellow and CTO for Enterprise Modernization Tools, Compilers and Security, to learn how IBM’s latest compilers, middleware and tools can help you stay on the technology curve. In this complimentary webcast, Ray and Kevin will discuss best practices and approaches to plan and execute a successful compiler migration, alongside CICS®, IMS™ and DB2® upgrades. They will also go over IBM’s strategy for compilers and tools on System z to help you... [More]
Enterprise PL/I for z/OS has consistently delivered innovations to help developers maintain and create applications optimized for deployment on IBM System z servers. Like COBOL, PL/I also focuses on delivering new features to improve performance, productivity, and modernization of proven, business critical applications. IBM has delivered a new release of the PL/I compiler every year since 1999 on System z. The announcement of Enterprise PL/I for z/OS V4.4 has kept this streak alive and reaffirms IBM's commitment to PL/I on... [More]
Code reviews were once common practice, but at some companies they have been reduced or even eliminated entirely. Often this
has been done in the name of cost savings even though the earlier a bug is found in the application life cycle, the less it costs.
Also, if you are still conducting code reviews, your coworkers are probably not perfect: they can miss
some errors and can overlook violations of your coding standards .
Fortunately, the Enterprise PL/I compiler can help you with the latter:
You can change the defaults for the RULES... [More]
One of the new options introduced in the new 4.2 release of Enterprise PL/I
is the UNROL L option. However, to understand it, you first need to understand
what the compiler does with loops.
Usually, the compiler turns a DO loop into a sequence of instructions which is
followed by a test and then a conditional branch back to repeat those instructions
with some updated values (and the sequence of instructions may be preceded by a
conditional test to see if the loop should be run at all).
In some situations, the optimizer can make this... [More]
For many years, the only floating point representation on z/OS was hexadecimal float. This is a base 16 representation, but most of us have 10 fingers and most business applications want to perform decimal calculations.
The difference between these 2 bases leads to problems as exemplified by this code:
dcl f1 float dec(6);
dcl f2 fixed dec(5,3);
dcl f3 float dec(6);
f1 = 4;
f2 = f1 / 100e0;
put skip data( f2 );
f3 = 100 * f2;
put skip data( f3 );
This rather disconcerting... [More]
Code that uses elements of structures with multiple REFERs can be very expensive : each reference uses one or more
costly library call to remap the structure. Many PL/I users have long known that the of multiple REFERs created a
black hole for performance.
Now, with Enterprise for z/OS 4.1, for structures where all the elements are byte-aligned, those calls will be avoided and
straightforward inline code generated (because if all elements are byte-aligned, no padding is possible and thus the
address calculations are relatively... [More]
Enterprise PL/I has always supported "named constants", i.e. scalars declared with the VALUE attribute, which make your
code more maintainable than using the constants as is, but which also allow the compiler to produce much better code
than scalars declared with the INITIAL attribute.
With Enterprise 4.1 (actually even with 3.9 although it was not documented then), you can now declare named constants in
structures (as long as all the leaf elements of such a structure have the VALUE attribute and as long as the structure... [More]
Are you looking for PL/I documentation across different releases? Do you want to access PL/I documentation of both the HTML and PDF format? The PL/I library pages now provide the following types of PL/I documentation in one central location: Announcement letters PDF documentation HTML documentation URL Start visiting the following PL/I library pages: Enterprise PL/I documentation library PL/I for AIX documentation library PL/I for MVS & VM PL/I for VSE
ALLOCATE is a storage control built-in function, which allocates storage of the specified size in the heap. You can also use ALLOCATE to allocate the specified size in the specified area. When you specify ALLOCATE (n) , ALLOCATE allocates storage of size n in heap storage and returns the pointer to the allocated storage. If necessary, n is converted to REAL FIXED BINARY (31,0) . If the requested amount of storage is not available, the STORAGE condition is raised. The ALLOCATE built-in function now has the AREA reference as a new... [More]
If you use the TEST option and DebugTool, Enterprise PL/I will show you the source as you coded it.
So, for example, if you have code that contains an EXEC SQL statement, you will see in the
debugger just that EXEC SQL statement as you coded it and not the many, many statements generated by the
preprocessor and visible in the listing. This is a big plus since those generated
statements will be largely meaningless to you and would certainly not be ones
you should be debugging and fixing.
The same would be true if you were using the CICS... [More]
In PL/I conversions, BINARY rules over DECIMAL, and FLOAT, over FIXED.
This means, for example, that when an expression contains a BINARY and a DECIMAL operand, then
the result will be BINARY.
Hence, for the assignment in this code
dcl a fixed bin;
dcl b float dec;
b = b + a ;
there will be these conversions
a will be converted to FLOAT BIN
b will be converted to FLOAT BIN
the sum will be converted to FLOAT DEC
PL/I has always had a series of built-in functions (BINARY, DECIMAL, FIXED, and FLOAT) to help
control such... [More]