ISERVE Stack Extensions and Functions

To facilitate the use of stacks, ISERVE provides extensions that are accessible through extended functions. These extensions do the following:

Provide each IMOD with multiple, fully addressable stacks. An IMOD can use from 1 to 230 stacks and switch freely between them. Unlike the NEWSTACK and DELSTACK commands, you do not need to delete the current stack to get to a previous one.
Let stacks receive TRACE and SAY output, making the output available to the program or program caller.
Permit access to a stack in random fashion, so that records can be read or written in any order.
Permit an IMOD task access to stacks that belong to other executing IMOD tasks. Coupled with the WAIT() function, this enables communication between concurrently executing IMOD tasks.

The following table lists the ISERVE stack functions.

Note: For more information about the stack functions, see the Reference Guide.

PUBSTACK(): Controls the use of a stack by external IMODs.
PULL(): Operates the same way as the PULL instruction in REXX, except that you can specify the stack number and the owning IMOD task ID.
PUSH(): Operates the same way as the PUSH instruction in REXX, except that you can specify the stack number and the owning IMOD task ID.
QUEUE(): Operates the same way as the QUEUE instruction in REXX, except that you can specify the stack number and the owning IMOD task ID.
QUEUES(): Operates the same way as the QUEUE() function, except that the entire contents of a stack are queued in a single operation.
REDIRECT(): Sends TRACE or SAY output to a stack.
SHOVE(): Inserts a record anywhere in any stack.
SORT(): Lets you sort stack records based on the contents of up to six fields.
STACKINF(): Returns information about stacks, including the IDs of all active stacks, and lets you change the maximum permissible size of a stack.
SWAPSTAK(): Controls which stack is currently in use.
TUG(): Enables reference to any record in any stack. TUG() obtains a copy of the record only; the record is not removed from the stack.
WAIT(): Lets an IMOD suspend processing. Processing is resumed only when an external IMOD writes one or more records to the waited‑upon stack or stacks.
YANK(): Enables reference to any record in any stack. It operates the same way as TUG(), except that the record is removed from the stack.