DECB support debuts in TPF/GI
TPF PUT 13 and higher support the concept of data event control blocks (DECBs). And now TPF/GI 2.6.1 provides powerful graphical tools that help programmers debug code that uses DECBs.
What is a DECB? DECBs act like data levels that can be created and released dynamically, that can be named, and that can grow as necessary. IBM created the DECB concept to address the archaic limitations of having only 16 data levels that cannot easily expand.
To accomodate the DECB concept, TPF/GI has redesigned its graphical ECB window. In the process, support for traditional data levels has been enhanced as well.
Redesigned ECB window
A new DECB area has been added to the graphical page of the ECB window. In this DECB area, each DECB is represented by a rectangle. The name of the DECB appears on the front of the rectangle. If a DECB contains a block, the rectangle representing it is red; otherwise, the rectangle is blue.
The size of the block owned by the DECB is indicated by a single character in parentheses beside the DECB name: for example, FARE QUOTE (4) means a 4K block is on the DECB named FARE QUOTE. (H) means a high speed block, (L) a large block, and (S) a small block.
The presence of detached blocks is signalled by a smaller red rectangle within the data level rectangle.
Using the DECB area
To edit the contents of detached blocks, programmers simply double click the smaller red rectangle. Similarly, to edit the DECB block itself, programmers can double click the main DECB rectangle.
Other operations on the DECB can be performed by right clicking or by using the memory chip, trash, and database icons in the lower right corner of the ECB window.
For example, dragging the memory chip and dropping it on a DECB level will get core for the DECB. Dragging a DECB to the trash will release the core block associated with DECB. Dragging the database icon to the DECB will do a FINDC.
Selecting a DECB level causes information about that level to be displayed in the one-line detail area below the DECB rectangles. The fields in this detail area can be double clicked or right clicked to explore DECB information in even more detail.
A similar one-line detail area has been added for the data level area as well.