The amount of memory used for the schema cache depends of number of objects (tables and stored procedures) and descriptors (columns and parameters) that are replicated. Each object and descriptor requires 128 bytes.
At start-up, Adaptive Server allocates 8K of memory—which is sufficient for 64 object or descriptors. Thereafter, memory is allocated in 2K chunks. Adaptive Server also allocates 2048 bytes for the hash table at start-up.
A “least recently used” (LRU) mechanism keeps the schema cache size manageable by removing from memory those objects/descriptors not recently referenced. Thus, RepAgent does not need enough memory to describe all replicated objects. At minimum, RepAgent needs enough memory to describe one replicated object.