ZCOM Tables and Data Structures

ZCOM Header Structure

HPZLU - ZLU table pointer (zlu_type *)

This is a pointer to the 1st entry in the ZLU table. Note that all of the ZLU table entries are stored in sequential order within kernel memory.

HPTTBL - Logical Terminal Table pointer (zltt_type *)

This is a pointer to the 1st Logical Terminal table. Note that all of the LTTs are stored in sequential order within kernel memory.

HPPTBL - Physical Terminal Table pointer (zptt_type *)

This is a pointer to the 1st physical terminal table. Note that all of the PTTs are stored in sequential order within kernel memory.

HPIFTP - Interface Table pointer (zift_type *)

This is a pointer to the first Interface Table (IFT). Note that all of the IFTs are stored in sequential order within kernel memory.

HPRESP - Pointer to the first response record (zrsp_type *)

This is a pointer to the first response record. Note that all of the response records are stored in sequential order within kernel memory.

HPQUES - Queue Header pointer (zqhd_type *)

This is a pointer to the first Queue Header. Note that all of the Queue Headers are stored in sequential order within kernel memory.

HPBFFR - Data buffer pointer (char *)

This is a pointer to the start of the data buffer pool. The data buffer pool is a block of contiguous kernel memory used for dynamically allocating data buffers for a variety of uses. The size of this block of memory is determined by the Buffer-Poolparameter from the TTGEN configuration file.

HPQLIM - Default program ZLU message queue limit

The default program ZLU message queue limit is the maximum number of messages that may be queued on each program ZLU. This value is initialized from the Queue-Limitparameter in the TTGEN configuration file. The default limit may be overridden during a zopen() by specifying a non-zero value in the limit parameter. The program ZLU queue limit may be changed dynamically by calling the zsetql() routine.

Chapter 3

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