Maximum allocated memory

WTSupported in traditional Synergy on Windows


USupported on UNIX


The MAXMEM environment variable specifies the maximum amount of memory (in bytes) that the runtime allocates for user program code and data before removing inactive segments from memory.


The maximum amount of memory (in bytes) that you want allocated before inactive memory segments are removed from memory.


The default value for MAXMEM on UNIX is 1,310,720 bytes (1.25 MB). The default value on Windows is 8,388,608 bytes (8 MB). On Windows, a MAXMEM minimum of 4 MB is enforced, even if an explicit, lower MAXMEM value has been specified. The maximum number of bytes that you can specify is limited by the memory available on your system.

Larger values may dramatically improve performance. Smaller values cause the memory segments to be released more often, slowing down performance but conserving memory.

If memory is not large enough to run the program after releasing all available segments, the internal value for maximum allocated memory is increased to be large enough to contain the minimum required program segments for execution. It is never reduced. If it exceeds any value specified by MAXMEMMAX, an error occurs.

If more than 10 segment reclamations occur in a one‑second interval, MAXMEM is automatically increased by 100,000. To see the current MAXMEM value for your program, use SHOW MEMORY in the debugger.

If MAXMEM is greater than 50,000,000, the runtime never reclaims segments. This is to assist with VAX DIBOL code migration, where records in routines are assumed to be static records.

To check whether memory reclamation is occurring with a specific value of MAXMEM, set the MEMDBG environment variable to 1. The system beeps on each reclamation.

On Windows, for optimal performance, set MAXMEM per program in the [myprog] section of your synergy.ini file. When UI Toolkit is installed, a MAXMEM setting of 16 MB (16 x 220) is added to the [COMPOSER] section of synergy.ini.

Setting location

The environment. On Windows, this environment variable can also be set in the [synergy], [dbr], or [myprog] section of synergy.ini (where myprog is any .dbr file).

Used by



On Windows, if set in the synergy.ini file,